Modify left fancy header also in the bibliography section

Question

When I change the behavior of \leftmark in the Reference section, it only changes on the second odd page of that section (by default, both \leftmark and \rightmark is set as \bibname). Compile the MWE below with

pdflatex -synctex=1 -interaction=nonstopmode -shell-escape %.tex|bibtex bu1.aux|bibtex bu2.aux|pdflatex -synctex=1 -interaction=nonstopmode -shell-escape %.tex|pdflatex -synctex=1 -interaction=nonstopmode -shell-escape %.tex

What is the reason for this?

\documentclass[b5paper, twoside, 11pt]{book}

\usepackage{fancyhdr}           % needed for fancy headers
\setlength{\headheight}{13.6pt}   % to avoid lame warning ...
\usepackage[sectionbib]{bibunits} % enable several bibliography. The sectionbib sets bibliography titles at section level
\usepackage{blindtext}
\begin{filecontents}{test.bib}
@article{test,
    author={A Dummy Reference},
    title = {\blindtext[7]},
    journal = {Some random Journal},
    year = {2013}
}
\end{filecontents}
\defaultbibliography{test}      % source for references
\renewcommand\bibname{References} % rename bibliography as references
\newtoks\paperTitle

\usepackage{titlesec}
\newcommand{\includePaper}[1]{
    \begin{bibunit}
        \part{\the\paperTitle}
        \vspace*{50pt}
        {\noindent\raggedright\normalfont\LARGE\bfseries\the\paperTitle\par\nobreak}
        \vspace*{40pt}
        \chaptermark{\the\paperTitle}
        #1 % contents
        \clearpage
        \putbib
        \sectionmark{References}   % <- I want this as \rightmark
        \chaptermark{\the\paperTitle} % <- I want this as \leftmark
        \cleardoublepage
    \end{bibunit}
}
\makeatletter
\renewcommand\thesection{\@arabic\c@section}
\@addtoreset{section}{part}
\makeatother
\titleformat{\section}[hang]{\bfseries\Large}{\thesection.\quad}{0pt}{}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\pagestyle{fancy}
\renewcommand{\chaptermark}[1]{\markboth{#1}{}}
\renewcommand{\sectionmark}[1]{\markright{#1}{}}
\fancyhf{}
\fancyhead[LE,RO]{\thepage}
\fancyhead[RE]{\nouppercase{\leftmark}}
\fancyhead[LO]{\nouppercase{\rightmark}}

\begin{bibunit}
\chapter*{Introduction}
\chaptermark{Introduction}
\section{First section in introduction}
\blindtext[10]\cite{test}
\clearpage
\putbib
\sectionmark{References}   % <- I want this as \rightmark
\chaptermark{Introduction} % <- I want this as \leftmark
\cleardoublepage
\end{bibunit}

\paperTitle{First paper title}%
\includePaper{\section{First section in paper}\blindtext[8]\cite{test}}
\end{document}

Answer 1

AFAIK the usage of running headers for the bibliography etc can not be disabled by a fancyhdr pagestyle. You could use pagestyle myheadings for those pages, but then the layout of the header is different, eg. there is no headsepline.

So here is a suggestion using package scrlayer-scrpage. Note that this package can not be used together with fancyhdr.

\documentclass[b5paper, twoside, 11pt]{book}

\usepackage[headsepline,automark,markcase=noupper]{scrlayer-scrpage}
\renewcommand*\chaptermarkformat{}
\renewcommand*\sectionmarkformat{}
\addtokomafont{pageheadfoot}{\normalfont}

\setlength{\headheight}{13.6pt}   % to avoid lame warning ...
\usepackage[sectionbib]{bibunits} % enable several bibliography. The sectionbib sets bibliography titles at section level
\usepackage{blindtext}
\begin{filecontents}{test.bib}
@article{test,
    author={A Dummy Reference},
    title = {\blindtext[7]},
    journal = {Some random Journal},
    year = {2013}
}
\end{filecontents}
\defaultbibliography{test}      % source for references
\renewcommand\bibname{References} % rename bibliography as references
\newtoks\paperTitle

\usepackage{titlesec}
\newcommand{\includePaper}[1]{
    \begin{bibunit}
        \part{\the\paperTitle}
        \vspace*{50pt}
        {\noindent\raggedright\normalfont\LARGE\bfseries\the\paperTitle\par\nobreak}
        \vspace*{40pt}
        \markboth{\the\paperTitle}{}
        #1 % contents
        \clearpage
        \KOMAoptions{manualmark}
        \markright{References}
        \putbib
        \cleardoublepage
        \KOMAoptions{automark}
    \end{bibunit}
}
\makeatletter
\renewcommand\thesection{\@arabic\c@section}
\@addtoreset{section}{part}
\makeatother
\titleformat{\section}[hang]{\bfseries\Large}{\thesection.\quad}{0pt}{}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\begin{bibunit}
\chapter*{Introduction}
\markleft{Introduction}
\section{First section in introduction}
\blindtext[14]\cite{test}
\clearpage
\KOMAoptions{manualmark}
\markright{References}
\putbib
\cleardoublepage
\KOMAoptions{automark}
\end{bibunit}

\paperTitle{First paper title}%
\includePaper{\section{First section in paper}\blindtext[8]\cite{test}}
\end{document}

---

You can also use package scrlayer-fancyhdr:

\documentclass[b5paper, twoside, 11pt]{book}

\usepackage{scrlayer-fancyhdr}           % needed for fancy headers
\pagestyle{fancy}
\renewcommand{\chaptermark}[1]{\markboth{#1}{}}
\renewcommand{\sectionmark}[1]{\markright{#1}{}}
\fancyhf{}
\fancyhead[LE,RO]{\thepage}
\fancyhead[RE]{\nouppercase{\leftmark}}
\fancyhead[LO]{\nouppercase{\rightmark}}

\setlength{\headheight}{13.6pt}   % to avoid lame warning ...
\usepackage[sectionbib]{bibunits} % enable several bibliography. The sectionbib sets bibliography titles at section level
\usepackage{blindtext}
\begin{filecontents}{test.bib}
@article{test,
    author={A Dummy Reference},
    title = {\blindtext[7]},
    journal = {Some random Journal},
    year = {2013}
}
\end{filecontents}
\defaultbibliography{test}      % source for references
\renewcommand\bibname{References} % rename bibliography as references
\newtoks\paperTitle

\usepackage{titlesec}
\newcommand{\includePaper}[1]{
    \begin{bibunit}
        \part{\the\paperTitle}
        \vspace*{50pt}
        {\noindent\raggedright\normalfont\LARGE\bfseries\the\paperTitle\par\nobreak}
        \vspace*{40pt}
        \chaptermark{\the\paperTitle}
        #1 % contents
        \clearpage
        \KOMAoptions{manualmark}
        \markright{References}   % <- I want this as \rightmark
        \putbib
        \cleardoublepage
        \KOMAoptions{automark}
    \end{bibunit}
}
\makeatletter
\renewcommand\thesection{\@arabic\c@section}
\@addtoreset{section}{part}
\makeatother
\titleformat{\section}[hang]{\bfseries\Large}{\thesection.\quad}{0pt}{}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\begin{bibunit}
\chapter*{Introduction}
\chaptermark{Introduction}
\section{First section in introduction}
\blindtext[14]\cite{test}
\clearpage
\KOMAoptions{manualmark}
\rightmark{References}   % <- I want this as \rightmark
\putbib
\cleardoublepage
\KOMAoptions{automark}
\end{bibunit}

\paperTitle{First paper title}%
\includePaper{\section{First section in paper}\blindtext[8]\cite{test}}
\end{document}