KDP says manuscript contains only images - cannot reflow text - requires fixed format

[meonkeys]

I generated an (awesome-looking) EPUB of my book and KDP rejects it.

Here's what KDP said when I uploaded EPUB output of https://github.com/meonkeys/shb :

Your manuscript contains only images. Use Kindle Create to export it as a fixed format comic or print replica in Kindle Package Format (KPF). Launch eBook previewer for more information.

So I tried that. The Kindle Previewer can open the EPUB and reads fairly well, albeit with a few idiosyncrasies. A couple SVG graphics were messed up (resized incorrectly, missing text), and cross-references to sidebars were dead links.

But when I try to upload the KPF file to KDP, I get this:

Same error as when I upload the EPUB. Again, oh well, I'm not even sure this matters to my target audience.