I played around with sideloading azw3 and I never seem to get the missing cover problem.
There was one instance tho where the cover of a book got changed to the one on Amazon's website. I read that the Kindle is basing the cover being displayed to the ASIN attached to the book. I make sure to have all my books in Calibre to have all their ISBNs and ASINs. Maybe that's why?
|