I converted an EPUB file to AZW3 (default settings, calibre 3.40.1).
Both the original EPUB and the converted AZW3 display in the calibre ebook viewer but when I send the AZW3 to the Kindle Paperwhite and click on the book cover it just stays in "Opening...." and I have to reset the reader to get it working again.
If I convert it to MOBI there's no such problem but it loses all typography. I have converted other EPUBs to AZW3 and they do open so there must be some problem with this particular file but I have no clue what it is
Here is the conversion log
https://pastebin.com/fX8FRFtz
And here is the resulting AZW3 that hangs the Kindle Paperwhite (fw. 5.9.7)
https://mega.nz/#!lzRySY4L!NA4o_hEnB...3-sy9v7ETg4-J4