Posted by gregturn on May 08, 2020; 12:40pm
URL: https://discuss.asciidoctor.org/asciidoctor-pdf-style-for-KDP-print-book-tp7789p7978.html

To wrap up my own part of this thread (and perhaps to answer the original Op's question),

I talked to KDP on the phone. Engineering support got back and told me the PDF file had "transparencies". Recommendations were to:

A) NOT overwrite previous instances of the same file. Instead, create a fresh, new file.
B) Remove "transparencies" from the file.

I tried (A), even though it felt like a long shot. No change. Still failed, after upload, to process the file.

For (B), after much searching, I decided to open the PDF inside LibreOffice Draw and "Export Directly to PDF". File size was about 65% smaller than original. Uploaded it to KDP Print. A minute later, it was successful!

It appears they want VERY simple PDF files and won't do it themselves. So you must.