singlehtml and pdfhtml formatting and images from code not showing

[pancakereport]

I'd like to get a single PDF copy of some UC Berkeley textbooks including https://github.com/data-8/textbook and https://github.com/prob140/textbook/.

Building the books locally with the basic jupyter-book build <path-to-book> command works just fine, however when I use --builder singlehtml or --builder pdfhtml, I end up with fairly ugly output and am missing images that are generated from code. The images don't appear, I just get a little image icon and a file path for where the image should be. When I use --builder singlehtml, I can see that the images do exist in _images.

Here's the PDF I'm generating now. You can see the issues with images in section 1.3.1: ugly-textbook.pdf.

Two years ago someone else generated a PDF copy of the Data 8 textbook that didn't have these issues: old-textbook.pdf.