Here is the thread:
https://www.mobileread.com/forums/sh...d.php?t=364995
Basically, I found that the books have to be flagged as PDOC. For azw3 you can use a utility to do that. I chose to convert to KFX, as that can be done during the calibre conversion process. (I didn't know any more about this until a short time ago when I bought my Scribe, and had to piece it all together for myself, so don't feel bad).