# Images not appearing in ShareLaTeX

I'm trying to help my students fix their paper, at some point they were able to get their images to display but all have disappeared from the pdf at this point and we're not sure why. ShareLaTeX leaves the appropriate space for each of them, and does not display any error; it's just blank where the image should be. No 'draft' options anywhere. Image will caption appropriately if put inside a figure environment, but still will not display. Any one of these fails to appear even if I delete the others/all other body content.

Example code:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[dvipdfmx]{graphicx}
\usepackage{float}
\usepackage{bmpsize}

\begin{document}
\includegraphics[width=.7\textwidth]{ImageName1.png}
\includegraphics[width=1\columnwidth, bb=0 0 90 90] {ImageName2.png}
\includegraphics[width=1\columnwidth, bb=0 0 100 100] {ImageName3.jpg}
\end{document}

They're also using the hyperref package, though that doesn't seem relevant...

Image is in the same folder as the tex file, fails to appear whether the file extension is included or not in the command.