PDF has no bookmarks despite correct .out file

I have the following minimal example:

\documentclass{article}

\usepackage[bookmarks=true]{hyperref}

\begin{document}

\tableofcontents

\section{Background}

Here is some Background.

\section{System}

This is the system under study.

\section{Results}

\subsection{Result 1}

We got some results.

\subsection{Result 2}

And then some more results.

\end{document}


I run it through pdflatex twice so that the .aux file will be correct. However, when I open the PDF, it has no bookmarks at all.

I did notice that the .out file was generated, and appears to be correct as far as I can tell:

\BOOKMARK [1][-]{section.1}{Background}{}% 1
\BOOKMARK [1][-]{section.2}{System}{}% 2
\BOOKMARK [1][-]{section.3}{Results}{}% 3
\BOOKMARK [2][-]{subsection.3.1}{Result 1}{section.3}% 4
\BOOKMARK [2][-]{subsection.3.2}{Result 2}{section.3}% 5


So, why don't these bookmarks show up in the PDF?

I've looked at several other SE questions regarding bookmarks, but none of them have helped resolve the issue.