The original bug I submitted pertained to animals not spawned with an egg. These are my farm animals that were bred naturally and they are not dropping XP.
This is still an issue in 1.16pre1
Sorry I try my best to use the search feature but nothing ever comes up.
I also encountered this bug yesterday.
I am on 1.16.1 and the difficulty is locked to hard. I found one zombie villager the second night and another the third night. One was also underground but I couldn't get to it. So maybe they either fixed this or you MUST be on Hard for the 5% to be true.