test_includepdf.tex

\documentclass[12pt]{article}
\usepackage{tikz}
%\usepackage{underscore} % Breaks if uncommented
\usepackage{grffile}
\usepackage{pdfpages}

\begin{document}

\includepdf[pagecommand=
{\begin{tikzpicture}[remember picture, overlay]
  \end{tikzpicture}}
,pages=1]{scans/Blank_blank.pdf}

\end{document}

%%% Local Variables:
%%% mode: latex
%%% TeX-master: "test_includepdf"
%%% End: