Blank pages for \includepdf{}

Question

I'm trying to include a scientific paper in an appendix in xelatex.

No errors from the package, no issues in the log file from pdfpages and it renders to pdf just fine - except that all the pages for the pdf that is meant to be included are blank. Page count is correct.

Some scientific papers, like this one, work but the one I need doesn't.

Note: It's not a font colour issue like in this question, there is no white text to highlight.

Appendix:

\chapter{Appendix}
\addcontentsline{toc}{chapter}{Apendix}
\section{Published manuscripts}

\subsection{Qualitative and quantitative assessment of the presence of ciguatoxin, P-CTX-1B, in Spanish Mackerel (\textit{Scomberomorus commerson}) from waters in New South Wales (Australia)}
\includepdf[pages={-}]{appendix/Drummond-06.PDF}

Pulled into main document (not all .cls info shown because it's quite long, if that's needed please let me know):

\documentclass[letterpaper,nonstopmode,draftmode]{simplethesisdissertation}

(title, authors)

% PDF settings and properties.
\hypersetup{
pdftitle={\DocumentTitle},
pdfauthor={\AuthorName},
pdfsubject={Ph.D. Thesis, University of Technology Sydney, 2018},
pdfcreator={XeLaTeX},
pdfproducer={},
pdfkeywords={},
unicode=true,
bookmarks=true,
bookmarksopen=true,
pdfstartview=FitH,
pdfpagelayout=OneColumn,
pdfpagemode=UseOutlines,
hidelinks,
breaklinks,
bookmarksnumbered}

\begin{document}

\input{appendix/appendix.tex}

\end{document}

Answer 1

It was a huge effort to reconstruct a MWE from what you provide, and it is not clear why you are in draft mode. That said, the MWE below and the problematical pdf you provide do not produce a problematical output. I am compiling with XeLatex with up-to-date Texlive on Windows 10.

\documentclass[letterpaper,nonstopmode,draftmode]{book}
\usepackage{pdfpages}

\begin{document}

\chapter{Appendix}
\addcontentsline{toc}{chapter}{Apendix}
\section{Published manuscripts}

\subsection{Qualitative and quantitative assessment of the presence of ciguatoxin, P-CTX-1B, in Spanish Mackerel (\textit{Scomberomorus commerson}) from waters in New South Wales (Australia)}
\includepdf[pages={-}]{Drummond-06.PDF}

\end{document}