Reproduced on 1.15 Pre-5
Also affects when Villagers turn into Villager Zombies
Confirmed in 1.15 Pre-5
Fixing this would resolve TPS lag on servers when villagers are running around hitting the bell continually.
Confirmed for 1.15 Pre-Release 3
Also does not support ctrl+v pasting of text when using the tab key to focus a field.
Just did some testing myself in 1.14.1 and restarted a bunch of times. No disappearances.... until my 10th or so restart. The issue is still confirmed as existing in 1.14.1 for me.
Today I lost a Mending/Silk Touch Villager (very cheap trades, too, at 2 and 3 emeralds each) and about 14 other Villagers. I have consistently been losing item frames, armor stands, and mobs. I would love for this issue to be resolved.
This bug happens for me as well.
I'm dumb. I searched before posting this and didn't find this other report until now: https://bugs.mojang.com/browse/MC-140594
I just tried this with a world updated from 18w22c to Pre-Release 1 and a newly generated Pre-Release 1 world, and it seems the bug is fixed for me. I had this same issue in 18w22b and 18w22c, but now my books remained as they were when I put them in a chest.
This occurred for me the other day in 18w22c
Ah, I see. That Bug is actually quite old and just keeps getting updated as recently as last year. I'll let this be closed, then.
This also happens to me when going between dimensions. I had a Feather Falling 1 and Mending books, and both became Protection 1 when I went from the Overworld to Nether and back again.
Have attached four debug report files/profiles. Using 1.15 pre-7 I get ~15 TPS with 100 Ravagers and 3 players.