There is a thread about the "half-screen-blank" issue here:
https://www.mobileread.com/forums/sho...d.php?t=199944
Also, I have observed the same problems described in this thread:
- half-blank-screen, especially before large <p>'s
- sudden font changes, not invoked in the EPUB code
- shifted bookmarks
- <em>'s rendered in bold by default, instead of the more common italics
- smallcaps gone (though I have to verify this point --- I haven't had time yet)