How to make section name appear in ToC when using both fancyhdr and titlesec

Question

We want the section Preface to appear on the TOC, but as can be seen on the following screenshot, the section name does not appear to be visible, although the dotted line is appearing with page number as well.

We are using the following lines, when we try to make the section appear in the ToC:

\input{sections/0_Preface}
\addcontentsline{toc}{section}{\hspace*{2.2em}\nameref{sec:preface}} % ---- ADDS PREFACE TO THE TOC

What may cause this is that we are using both titlesec and fancyhdr together, although they are in conflict with each other. If we remove the titlesec package, the section name suddenly appears in the TOC:

How do we make the section name appear in the TOC when still using titlesec and fancyhdr? We need fancyhdr for header, footer etc. and titlesec for changing font size of sections.

MWE

\documentclass[11pt, report]{report}

\usepackage[english]{babel}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\graphicspath{ {./figures/} }
\usepackage{lastpage}
\usepackage{array}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{float}

\usepackage[pagestyles]{titlesec} % <------ This here 
\titleformat{\section}{\bfseries\LARGE}{\hspace{1ex}\Huge\thesection}{2ex}{} %<--- changes font size of sections

\usepackage{fancyhdr} %<---- Before that there
\usepackage{color}
\usepackage{hyperref}
\usepackage{lastpage,refcount,atbegshi}
\usepackage{lipsum}

\title{Header}   % Title
\author {Ahmad Ahmadsen} % Author
\date{\today} % Date

\makeatletter
\let\mytitle\@title
\let\theauthor\@author
\let\thedate\@date
\makeatother

\pagestyle{fancy} 
\fancyhf{} 
\lhead{\mytitle} 

\rfoot{\thepage \space} 
\lfoot{University} 

\begin{document}

\pagenumbering{Roman} 

\input{sections/0_Preface}
\addcontentsline{toc}{section}{\hspace*{2.2em}\nameref{sec:preface}} % ---- ADDS PREFACE TO THE TOC

\cfoot{\thepage \space of \pageref{LastPage}}
\rfoot{} 
\lfoot{} 

\renewcommand \thesection{\arabic{section}}

\pagenumbering{gobble}

\pagenumbering{arabic}

\vspace*{-20em}\tableofcontents\numberline{} 

%\tableofcontents
\thispagestyle{empty}

\clearpage
\setcounter{page}{1}
\setcounter{tocdepth}{3}
\newpage


% Add sections here!
\section{Introduction}
\subsection{Motivation}
\subsection{Research Question}

\newpage

\section{Analysis}
\subsection{analys 1}
\subsection{analys 2}
\subsection{analys 3}

\end{document}

0_Preface File:

\section*{Preface} \label{sec:preface}

\clearpage

Answer 1

Update:

This appears to be a conflict between the packages hyperref, nameref (loaded by hyperref) and titlesec (see https://tex.stackexchange.com/a/397032/113546). So I used the solution given there to resolve the conflict.

\makeatletter
\newcommand*{\starsection}[1]{%
  \section*{#1}%
  \NR@gettitle{#1}%
}
\makeatother

and then use \starsection instead of \section*

• Removed the pagestyles option
• Replaced the \input{sections/0_Preface} with

\chapter*{Preface}
\label{sec:preface}

• renamed \thetitle to \TheTitle.
• removed the redefinitions of the footer fields.
• And, by the way, this problem would have disappeared if you had written Preface instead of \nameref{sec:preface} in \addcontentsline. You can still make it easier by adding the \addcontentsline call to the \starsection macro and using #1 there instead of the \nameref{sec:preface}. See the second solution below.

\documentclass[11pt, report]{report}

\usepackage[english]{babel}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\graphicspath{ {./figures/} }
\usepackage{lastpage}
\usepackage{array}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{float}

\usepackage{titlesec}
\titleformat{\section}{\bfseries\LARGE}{\hspace{1ex}\Huge\thesection}{2ex}{} %<--- changes font size of sections

\usepackage{fancyhdr}
\usepackage{color}
\usepackage{hyperref}
\usepackage{lastpage,refcount,atbegshi}
\usepackage{lipsum}

\title{Header}   % Title
\author {Ahmad Ahmadsen} % Author
\date{\today} % Date

\makeatletter
\newcommand*{\starsection}[1]{%
  \section*{#1}%
  \NR@gettitle{#1}%
}
\let\TheTitle\@title
\let\TheAuthor\@author
\let\TheDate\@date
\makeatother

\pagestyle{fancy} 
\fancyhf{} 
\lhead{\TheTitle} 

\rfoot{\thepage \space} 
\lfoot{University} 

\begin{document}

\pagenumbering{Roman} 

%\input{sections/0_Preface}
\starsection{Preface} 
\label{sec:preface}
\addcontentsline{toc}{section}{\hspace*{2.2em}\nameref{sec:preface}} % ---- ADDS PREFACE TO THE TOC

% \cfoot{\thepage \space of \pageref{LastPage}}
% \rfoot{} 
% \lfoot{} 

\renewcommand \thesection{\arabic{section}}

\pagenumbering{gobble}

\pagenumbering{arabic}

\vspace*{-20em}\tableofcontents\numberline{} 

%\tableofcontents
\thispagestyle{empty}

\clearpage
\setcounter{page}{1}
\setcounter{tocdepth}{3}
\newpage


% Add sections here!
\section{Introduction}
\subsection{Motivation}
\subsection{Research Question}

\newpage

\section{Analysis}
\subsection{analys 1}
\subsection{analys 2}
\subsection{analys 3}

\end{document}

Version with \contentsline added to \starsection macro:

\documentclass[11pt, report]{report}

\usepackage[english]{babel}
\usepackage[utf8]{inputenc}
\usepackage{graphicx}
\graphicspath{ {./figures/} }
\usepackage{lastpage}
\usepackage{array}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{float}

\usepackage{titlesec}
\titleformat{\section}{\bfseries\LARGE}{\hspace{1ex}\Huge\thesection}{2ex}{} %<--- changes font size of sections

\usepackage{fancyhdr}
\usepackage{color}
\usepackage{hyperref}
\usepackage{lastpage,refcount,atbegshi}
\usepackage{lipsum}

\title{Header}   % Title
\author {Ahmad Ahmadsen} % Author
\date{\today} % Date

\makeatletter
\newcommand*{\starsection}[1]{%
  \section*{#1}%
  \NR@gettitle{#1}%
  \addcontentsline{toc}{section}{\hspace*{2.2em}#1}%
}
\let\TheTitle\@title
\let\TheAuthor\@author
\let\TheDate\@date
\makeatother

\pagestyle{fancy} 
\fancyhf{} 
\lhead{\TheTitle} 

\rfoot{\thepage \space} 
\lfoot{University} 

\begin{document}

\pagenumbering{Roman} 

%\input{sections/0_Preface}
\starsection{Preface} 
\label{sec:preface}

% \cfoot{\thepage \space of \pageref{LastPage}}
% \rfoot{} 
% \lfoot{} 

\renewcommand \thesection{\arabic{section}}

\pagenumbering{gobble}

\pagenumbering{arabic}

\vspace*{-20em}\tableofcontents\numberline{} 

%\tableofcontents
\thispagestyle{empty}

\clearpage
\setcounter{page}{1}
\setcounter{tocdepth}{3}
\newpage


% Add sections here!
\section{Introduction}
\subsection{Motivation}
\subsection{Research Question}

\newpage

\section{Analysis}
\subsection{analys 1}
\subsection{analys 2}
\subsection{analys 3}

\end{document}