It sounds similar, or the same, as an issue I reported last year in Feb 2019. The problem has improved for me over time, although not all the bugs. I think software has just been glitchier over the past year or something. I could not find a solution, it just started clearing up (sometimes) --- my post here,
https://www.mobileread.com/forums/sh...08&postcount=2 My 2nd post here was the issue with KU books not clearing. Mine could still be opened and read once returned when bugging out.