When calibre sidelods a book, I assume the Personal banner is missing? That means an ASIN was embedded. But the wrong one -- it will have been randomly generated. The Kindle is likely looking up the ASIN as an intermediate step to finding the book on Goodreads.
If it is actually a PDOC, I don't know if Amazon officially supports that anyway. If it comes to that, probaly not...
If you make sure the calibre metadata includes a correct amazon identifier, the Quality Check plugin will embed that as the ASIN, and hopefully the Kindle will stop being confused.
At least, if my
guess is correct.

I don't have a KPW to test my theory.
Edit: Beaten.

Great minds think alike.