We have two iPads, recent models, with the latest IOS. Both have everything logged in to the same Apple ID. On a MacBook Pro (MBP) with the latest MacOS, iTunes and iBooks (and everything else) are also on the same Apple ID. On all three, iCloud is set to store all the books. Yet when an eBook or PDF is added on the MBP, it seems to be random whether it will appear on one iPad, both, or neither. And when syncing, iTunes won’t show some of the books as existing in the library to be synced.
What is going on and how do I fix it?