Strange behavior of \caption when diacritics are used

Question

I'm having a disturbing issue with \caption when there are diacritics characters in the image caption. The diacritics are displayed just fine, but the caption itself is becomes justified on the left, not centered in those cases. Any idea why my environment is causing such a behavior in caption?

Here is the relevant document class I'm using.

\ProvidesClass{phdthesis}
%%
%% Base document style and options.
%%
\LoadClass[12pt,a4paper,titlepage,twoside,openright,fleqn]{book}
%%
%% Page margins
%%
%\RequirePackage[top=3cm,bottom=3cm,left=3.2cm,right=3.2cm,headsep=12pt,a4paper]{geometry}
%%
%% Color definitions
%%
\RequirePackage[svgnames]{xcolor}
\definecolor{mainColor}{RGB}{206,0,124} % You may redefine mainColor to suit your needs
%%
%% Font settings
%%
\RequirePackage[utf8]{inputenc}
\RequirePackage{fix-cm}
\RequirePackage[OT1,T1]{fontenc}
\RequirePackage[scaled]{helvet}
\renewcommand*\familydefault{\sfdefault}
\RequirePackage{microtype}
%\RequirePackage[english]{babel}
\RequirePackage[brazilian]{babel}
\RequirePackage[autostyle]{csquotes}

%% Bibliography settings

\RequirePackage[style=alphabetic,sorting=nyt,sortcites=true,autopunct=true,abbreviate=false,backref=true,backend=biber]{biblatex}
\defbibheading{bibempty}{}

%% Index settings

\RequirePackage{calc}
\RequirePackage{makeidx}
\makeindex
%%
%% Title page
%%
\RequirePackage{pdfpages}
\RequirePackage{graphicx}
\RequirePackage{tikz}
\RequirePackage{eso-pic}
\newcommand{\printtitlepage}[3]{%
\begingroup
\thispagestyle{empty}
\AddToShipoutPicture*{\put(0.5,0.5){\includegraphics[width=\paperwidth,height=\paperheight,keepaspectratio]{#1}}} % Image background
\centering
\vspace*{9cm}
\par\normalfont\fontsize{35}{35}\sffamily\selectfont
{#2}\par % Document title
\vspace*{1cm}
{\Huge {#3}}\par % Author name
\endgroup}
\newcommand{\HRule}[1]{\hfill \rule{0.2\linewidth}{#1}}

%% Main table of contents
\RequirePackage{titlesec}
\RequirePackage{titletoc}
\contentsmargin{0cm} % Removes the default margin
% Chapter text styling

\titlecontents{chapter}[1.25cm] % Indentation
{\addvspace{15pt}\large\sffamily\bfseries} % Spacing and font options for chapters
{\color{mainColor!60}\contentslabel[\Large\thecontentslabel]{1.25cm}\color{mainColor}} % Chapter number
{}  
{\color{mainColor!60}\normalsize\sffamily\bfseries\;\titlerule*[.5pc]{.}\;\thecontentspage} % Page number
% Section text styling
\titlecontents{section}[1.25cm] % Indentation
{\addvspace{5pt}\sffamily\bfseries} % Spacing and font options for sections
{\contentslabel[\thecontentslabel]{1.25cm}} % Section number
{}
{\sffamily\hfill\color{black}\thecontentspage} % Page number
[]
% Subsection text styling
\titlecontents{subsection}[1.25cm] % Indentation
{\addvspace{1pt}\sffamily\small} % Spacing and font options for subsections
{\contentslabel[\thecontentslabel]{1.25cm}} % Subsection number
{}
{\sffamily\;\titlerule*[.5pc]{.}\;\thecontentspage} % Page number
[] 

%% Chapter table of contents
% Section text styling
\titlecontents{lsection}[0em] % Indendating
{\footnotesize\sffamily} % Font settings
{}
{}
{}
% Subsection text styling
\titlecontents{lsubsection}[.5em] % Indentation
{\normalfont\footnotesize\sffamily} % Font settings
{}
{}
{}
%%
%% Page headers
%%
\RequirePackage{fancyhdr} % Required for header and footer configuration
\pagestyle{fancy}
\renewcommand{\chaptermark}[1]{\markboth{\sffamily\normalsize\bfseries #1}{}} % Chapter text font settings
\renewcommand{\sectionmark}[1]{\markright{\sffamily\normalsize\thesection\hspace{5pt}#1}{}} % Section text font settings
\fancyhf{} \fancyhead[LE,RO]{\sffamily\normalsize\thepage} % Font setting for the page number in the header
\fancyhead[LO]{\rightmark} % Print the nearest section name on the left side of odd pages
\fancyhead[RE]{\leftmark} % Print the current chapter name on the right side of even pages
\renewcommand{\headrulewidth}{0.5pt} % Width of the rule under the header
\addtolength{\headheight}{2.5pt} % Increase the spacing around the header slightly
\renewcommand{\footrulewidth}{0pt} % Removes the rule in the footer
\fancypagestyle{plain}{\fancyhead{}\renewcommand{\headrulewidth}{0pt}} % Style for when a plain pagestyle is specified
% Removes the header from odd empty pages at the end of chapters
\makeatletter
\renewcommand{\cleardoublepage}{
\clearpage\ifodd\c@page\else
\hbox{}
\vspace*{\fill}
\thispagestyle{empty}
\newpage
\fi}
\makeatother
%%
%% Chapter headers
%%
\makeatletter
\newcommand{\thechapterimage}{}
\newcommand{\chapterimage}[1]{\renewcommand{\thechapterimage}{#1}}
\def\thechapter{\arabic{chapter}}
\def\@makechapterhead#1{
\thispagestyle{empty}
{\centering \normalfont\sffamily
\ifnum \c@secnumdepth >\m@ne
\if@mainmatter
\startcontents
\begin{tikzpicture}[remember picture,overlay]
\node at (current page.north west)
{\begin{tikzpicture}[remember picture,overlay]

\node[anchor=north west,inner sep=0pt] at (0,0) {\includegraphics[width=\paperwidth]{\thechapterimage}};
% box decor
%\draw[fill=white,opacity=.6] (1cm,0) rectangle (8cm,-7cm);
%\node[anchor=north west] at (1cm,0) {\parbox[t][8cm][t]{6.5cm}{\huge\bfseries\flushleft \printcontents{l}{1}{\setcounter{tocdepth}{1}}}};

% title decor
\draw[anchor=west] (5cm,-9cm) node [rounded corners=25pt,fill=white,fill opacity=.6,text opacity=1,draw=mainColor,draw opacity=1,line width=2pt,inner sep=15pt]{\huge\sffamily\bfseries\textcolor{black}{\thechapter\ ---\ #1\vphantom{plPQq}\makebox[22cm]{}}};
\end{tikzpicture}};
\end{tikzpicture}}\par\vspace*{230\p@}
\fi
\fi
}
\def\@makeschapterhead#1{
\thispagestyle{empty}
{\centering \normalfont\sffamily
\ifnum \c@secnumdepth >\m@ne
\if@mainmatter
\startcontents
\begin{tikzpicture}[remember picture,overlay]
\node at (current page.north west)
{\begin{tikzpicture}[remember picture,overlay]
\node[anchor=north west] at (-4pt,4pt) {\includegraphics[width=\paperwidth]{\thechapterimage}};
\draw[anchor=west] (5cm,-9cm) node [rounded corners=25pt,fill=white,opacity=.7,inner sep=15.5pt]{\huge\sffamily\bfseries\textcolor{black}{\vphantom{plPQq}\makebox[22cm]{}}};
\draw[anchor=west] (5cm,-9cm) node [rounded corners=25pt,draw=mainColor,line width=2pt,inner sep=15pt]{\huge\sffamily\bfseries\textcolor{black}{#1\vphantom{plPQq}\makebox[22cm]{}}};
\end{tikzpicture}};
\end{tikzpicture}}\par\vspace*{230\p@}
\fi
\fi
}
\makeatother

%%
%% Section numbering format
%%
\makeatletter
\renewcommand{\@seccntformat}[1]{\llap{\textcolor{mainColor}{\csname the#1\endcsname}\hspace{1em}}}                    
\renewcommand{\section}{\@startsection{section}{1}{\z@}
{-4ex \@plus -1ex \@minus -.4ex}
{1ex \@plus.2ex }
{\normalfont\large\sffamily\bfseries}}
\renewcommand{\subsection}{\@startsection {subsection}{2}{\z@}
{-3ex \@plus -0.1ex \@minus -.4ex}
{0.5ex \@plus.2ex }
{\normalfont\sffamily\bfseries}}
\renewcommand{\subsubsection}{\@startsection {subsubsection}{3}{\z@}
{-2ex \@plus -0.1ex \@minus -.2ex}
{0.2ex \@plus.2ex }
{\normalfont\small\sffamily\bfseries}}                        
\renewcommand\paragraph{\@startsection{paragraph}{4}{\z@}
{-2ex \@plus-.2ex \@minus .2ex}
{0.1ex}
{\normalfont\small\sffamily\bfseries}}
\makeatother
%%
%% Special environments (definition, exercise, example, furtherinfo)
%%
\RequirePackage{amsmath,amsfonts,amssymb,amsthm}
\RequirePackage[framemethod=default]{mdframed}
\makeatletter
\newtheoremstyle{mainColornum} % Theorem style name
{7pt} % Space above
{7pt} % Space below
{\normalfont} % Body font
{} % Indent amount
{\small\bf\sffamily\color{mainColor}} % Theorem head font
{\;\;} % Punctuation after theorem head
{0.25em} % Space after theorem head
{\small\sffamily\color{mainColor}\thmname{#1}\thmnumber{\@ifnotempty{#1}{ }\@upn{#2}} % Theorem text (e.g. Theorem 2.1)
\thmnote{\ {\the\thm@notefont\sffamily\bfseries\color{black}--- #3.}}} % Optional theorem note
\renewcommand{\qedsymbol}{$\blacksquare$} % Optional qed square
%
\newtheoremstyle{blacknum} % Theorem style name
{7pt} % Space above
{7pt} % Space below
{\normalfont} % Body font
{} % Indent amount
{\small\bf\sffamily} % Theorem head font
{\;\;} % Punctuation after theorem head
{0.25em} % Space after theorem head
{\small\sffamily\thmname{#1}\thmnumber{\@ifnotempty{#1}{ }\@upn{#2}} % Theorem text (e.g. Theorem 2.1)
\thmnote{\ {\the\thm@notefont\sffamily\bfseries--- #3.}}} % Optional theorem note
\renewcommand{\qedsymbol}{$\blacksquare$} % Optional qed square
\makeatother
% Defines the special environments text styles to one of the two styles above
\theoremstyle{mainColornum}
\newtheorem{definitionT}{Definition}[chapter]
\newtheorem{exerciseT}{Exercise}[chapter]
\theoremstyle{blacknum}
\newtheorem{exampleT}{Example}[chapter]
\newtheorem{furtherinfoT}{Further Information}[chapter]
% Definition box
\newmdenv[skipabove=7pt,
skipbelow=7pt,
backgroundcolor=black!5,
linecolor=mainColor,
innerleftmargin=5pt,
innerrightmargin=5pt,
innertopmargin=5pt,
leftmargin=0cm,
rightmargin=0cm,
innerbottommargin=5pt]{dBox}
% Exercise box    
\newmdenv[skipabove=7pt,
skipbelow=7pt,
rightline=false,
leftline=true,
topline=false,
bottomline=false,
backgroundcolor=mainColor!10,
linecolor=mainColor,
innerleftmargin=5pt,
innerrightmargin=5pt,
innertopmargin=5pt,
innerbottommargin=5pt,
leftmargin=0cm,
rightmargin=0cm,
linewidth=4pt]{eBox}
% Example box
\newmdenv[skipabove=10pt,
skipbelow=10pt,
rightline=false,
leftline=true,
topline=false,
bottomline=false,
linecolor=mainColor,
innerleftmargin=5pt,
innerrightmargin=5pt,
innertopmargin=0pt,
leftmargin=0cm,
rightmargin=0cm,
linewidth=4pt,
innerbottommargin=0pt]{sBox}
% Further Info box
\newmdenv[skipabove=7pt,
skipbelow=7pt,
rightline=false,
leftline=true,
topline=false,
bottomline=false,
linecolor=gray,
backgroundcolor=black!5,
innerleftmargin=5pt,
innerrightmargin=5pt,
innertopmargin=5pt,
leftmargin=0cm,
rightmargin=0cm,
linewidth=4pt,
innerbottommargin=5pt]{iBox}
% Creates the special environments assigning a text style and a colored box style
\newenvironment{definition}{\begin{dBox}\begin{definitionT}}{\end{definitionT}\end{dBox}}
\newenvironment{exercise}{\begin{eBox}\begin{exerciseT}}{\hfill{\color{mainColor}\tiny\ensuremath{\blacksquare}}\end{exerciseT}\end{eBox}}
\newenvironment{example}{\begin{sBox}\begin{exampleT}}{\hfill{\color{mainColor}\tiny\ensuremath{\blacksquare}}\end{exampleT}\end{sBox}} 
\newenvironment{furtherinfo}{\begin{iBox}\begin{furtherinfoT}}{\hfill{\tiny\ensuremath{\blacksquare}}\end{furtherinfoT}\end{iBox}}  
\newenvironment{remark}{\par\vskip10pt\small % Vertical white space above the remark and smaller font size
\begin{list}{}{
\leftmargin=35pt % Indentation on the left
\rightmargin=25pt}\item\ignorespaces % Indentation on the right
\makebox[-2.5pt]{\begin{tikzpicture}[overlay]
\node[draw=mainColor!60,line width=1pt,circle,fill=mainColor!25,font=\sffamily\bfseries,inner sep=2pt,outer sep=0pt] at (-15pt,0pt){\textcolor{mainColor}{R}};\end{tikzpicture}} % Orange R in a circle
\advance\baselineskip -1pt}{\end{list}\vskip5pt} % Tighter line spacing and white space after remark



%% Make mybox 
\makeatletter
\newcommand{\distas}[1]{\mathbin{\overset{#1}{\kern\z@\sim}}}%
\newsavebox{\mybox}\newsavebox{\mysim}
\newcommand{\distras}[1]{%
  \savebox{\mybox}{\hbox{\kern3pt$\scriptstyle#1$\kern3pt}}%
  \savebox{\mysim}{\hbox{$\sim$}}%
  \mathbin{\overset{#1}{\kern\z@\resizebox{\wd\mybox}{\ht\mysim}{$\sim$}}}%
}

%% Misc
\usepackage{enumitem} % Customize lists
\setlist{nolistsep} % Reduce spacing between bullet points and numbered lists
\usepackage{booktabs} % Required for nicer horizontal rules in tables
\usepackage{parskip}  % Inclui \bigskip para cada linha vazia
%\usepackage{subfig} % Inclui \subfigure and \subcaptionbox environment
\usepackage{float}
\usepackage{subcaption}
\usepackage[export]{adjustbox}




%% Copyright
\newcommand{\printcopyright}[3]{%
~\vfill
\thispagestyle{empty}
\noindent Copyright \copyright\ {#1}, {#2}\\
\noindent \textsc{This is a \LaTeX{} document template -- Designed by Daniel Marcelino (CC BY ND-3.0)}\\
\noindent \textit{First edition, {#1}}}
%%
\endinput

I'm using RStudio RMarkdown to output my document. Here is the offending case:

---
output: pdf_document
documentclass: phdthesis
---

\newpage
## Professora Sonia Brüsch (PSDC)\index{PSDC}

\begin{figure}[ht!]
\centering
\subcaptionbox{Mapa da Votação}{
  \includegraphics[width=.98\linewidth]{figures/Cabos/2016/MAPA_13.pdf}}
  \makebox[0pt][r]{\raisebox{16mm}{\includegraphics[height=35mm]{figures/Cabos/2016/Legenda.pdf}}\hspace{12mm}}
\medskip
\subcaptionbox{Informações do Candidato}{
  \includegraphics[width=75mm,height=30mm]{figures/Cabos/2016/13_INFO_CAND.jpg}
  }\quad
\subcaptionbox{Medidas de Desempenho Eleitoral}{
  \includegraphics[width=73mm,height=30mm]{figures/Cabos/2016/13_INFO_ELEIT.jpg}
  }
\caption{Análise de Desempenho Eleitoral\\Professora Sonia Br$ü$sch (PSDC), Curitiba, 2016}
\end{figure}

Which produces the following not so nice justified caption:

Answer 1

Normally multiline captions are justified. If you want it centered, you need to use \captionsetup{justification=centering}.

Note: Some of the changes are purely gratuitous.

\documentclass{book}
\usepackage[utf8]{inputenc}
%\RequirePackage{fix-cm}
\usepackage[OT1,T1]{fontenc}
\usepackage[scaled]{helvet}
\renewcommand*\familydefault{\sfdefault}
\usepackage{microtype}
%\RequirePackage[english]{babel}
\usepackage[brazilian]{babel}
\usepackage{caption}
\usepackage{subcaption}
\usepackage[demo]{graphicx}
\usepackage{showframe}
\begin{document}

\begin{figure}[ht!]
\centering
\subcaptionbox{Mapa da Votação}{
  \includegraphics[width=.98\linewidth]{figures/Cabos/2016/MAPA_13.pdf}}
  \llap{\raisebox{16mm}{\includegraphics[height=35mm]{figures/Cabos/2016/Legenda.pdf}}\hspace{12mm}}
\medskip
\subcaptionbox{Informações do Candidato}{
  \includegraphics[width=75mm,height=30mm]{figures/Cabos/2016/13_INFO_CAND.jpg}
  }\quad
\subcaptionbox{Medidas de Desempenho Eleitoral}{
  \includegraphics[width=73mm,height=30mm]{figures/Cabos/2016/13_INFO_ELEIT.jpg}
  }
\captionsetup{justification=centering}
\caption{Análise de Desempenho Eleitoral\\Professora Sonia Br\"usch (PSDC), Curitiba, 2016}
\end{figure}

\end{document}