THis is the response that came yesterday evening from my complaint about categories changing and being reduced without publishing.
Supposedly books that had more than 2 categories were not supposed to be touched unless/until republished (that was latest that I could find).
If I had to guess I would suspect someone published a software update related to limiting categories that futzed things up and they are trying to figure out how to fix it.
I'm sorry for the trouble you are experiencing as a result of your book being
removed from certain categories, I've reported your case to our technical team,
additionally take into consideration that this is not related to late updates nor new
legislation, it is a general issue.
Please rest assured that our technical team is aware of this problem and is diligently
working hard to fix it as soon as possible.
Thanks for your patience while we fix this problem.
It is also hiding visibility to some of my books, they no longer show up on SalesRankExpress and i've had zero sales since the glitch.
Sigh! A good reason to want to limit ones books to KDP Select, so only Amazon has control of your sales, huh?