\documentclass{report}

\usepackage{titlesec}  % <-- das titlesec-Paket ist die Ursache

\usepackage{hyperref}

\begin{document}
\setcounter{tocdepth}{10}
\tableofcontents

\chapter{Foo Chapter}\label{chp:foo}
\section{Foo Section}\label{sec:foo}
Section~\nameref{sec:foo} in chapter \nameref{chp:foo}.

%\setcounter{secnumdepth}{10}
\part{PART}\label{part}

\chapter{CHAPTER}\label{chapter}

\section{SECTION}\label{section}

\subsection{SUBSECTION}\label{subsection}

\subsubsection{SUBSUBSECTION}\label{subsubsection}
Hello

\paragraph{PARAGRAPH}\label{paragraph}
Hello

\subparagraph{SUBPARAGRAPH}\label{subparagraph}
\end{document}
