All enchanted books change to protection when fished, reloaded or upgraded from an old version

Confirmed upgrading my server from 18w22a to 18w22b. We had a mending villager that became a Protection villager, books have changed to Protection, bows have changed to protection. "New" stuff generated is as expected. We are rolling the server back to confirm what was before the upgrade. I can redo the upgrade on a private copy of the world to see what specific cases of enchantments turn, and I would be happy to upload the old world copy for testing the upgrade if appropriate.  My wife reports all Librarian books are Protection. So... yeah. Rolling back to the backup.

EDIT: Oh, please edit the subject to be, "...when upgrading 18w21-A- to 18w22b". This bug may not happen with other releases or snapshots. It appears to be relevant only to yesterday's 22a snapshot so far.

EDIT2: I meant ... nevermind, but this happened between 18w22a as well, so a slightly different subject title may be more appropriate.

This happens on first world save. It's fine on initial load. It changes when the world is saved, exited then return.

This is serious bacause it DOES affect upgrading between 1.12.2 and 18w22b- you will only see it if you load a 1.12.2 world in the snapshot, save, then reload the game in the snapshot a second time. 

Steps to reproduce:

1: Load a world in 1.12.2.

2: Place ~5 (non-Protection) enchanted books in player inventory.

3: Place ~5 (non-Protection) enchanted books in a chest.

4: Spawn or find librarian villagers & unlock librarian trades.

5: Make note of current librarian trades. 

6: Save world & close game.

7: Reload world in 18w22b.

8: See librarian trades, books in inventory and books in chest(s) have not changed. 

9: Save world & close game. 

10: Reload world again in 18w22b.

11: See books in inventory have not changed, but all villager trades and books in chest(s) are Protection I-V.

Please fix this!

After switching from 18w22a to 18w22b on our server, we never rebooted before we began to notice "oddness." My wife was in a hurry to have me see the Mending villager she and a friend had found, only to find it a Protection villager now. The bug may trigger differently depending upon if it's a single-player load or server start-up. Our server never "saved" before I was shutting it down to rip out 22b for 22a and restore the world as it was.

Affects upgrading to 18w22b from 1.12, or any of the aquatic update snapshots. This also affects upgrading to 18w22c. 

Additional info: Some have said this does not affect newly spawned villagers. This is false. When you first encounter or spawn-egg new librarian villagers in snapshot 18w22b or 18w22c, they will offer a varied assortment of book trades. HOWEVER: if you leave the area, then return to the villagers, you will find they have all become protection. This isn't even an upgrade specific issue, because it affects new worlds generated in 18w22b or 18w22c too.

Steps to reproduce:

1: Create new world in 18w22b or (18w22c) with random seed. 

2: Spawn or find librarian villagers & unlock librarian trades.

3: Place various enchanted books in a chest. 

4: Save world & close game. 

5: Reload world in snapshot selected in step 1.

6: See all villager trades and books in chest(s) are Protection I-V.

Note: The level of protection listed after the change will correspond to the level of whatever enchantment the book/villager originally had. For example, Impaling V becomes Protection V, Efficiency III will become Protection III, Mending will become Protection I. 

not only friom 1.12.2,said it yesterday

I also encountered one of the enchanted pickaxes that I had in a chest changing to have the three enchantments become Protection V, Protection III, and Protection III... Screenshot attached

Same problem here. I got those enchanted books by fishing, though. The pics are from 18w22c.

I am on Buffet and in an ocean world. Started on 18w22c, I caught some enchanted books with fishing. One had thorns 2 and protection 3 on it. it is now protection 2 and protection 3.

It seemed to have happened upon restarting the server.

Edit: Server restart did not change the book while in inventory. Try putting it in a chest.

Having same issues

Okay I can Finally reproduce the bug.
1: Place enchanted books in chest.
2: Go to the nether or shut down the server or anything to unload the chunks.

3: Reload to Protection books.

It is written 4 days ago

I can confirm that this is still affecting Librarian villagers in 18w22c.  Librarians had various trades including Mending, Efficiency V for books.  After a full server restart, all of their trades have become various levels of Protection. 

This is a dedicated multiplayer server that is not ordinarily shut down, however it was recently migrated from one hosting provider to another.  The issue appears to have happened during the shutdown for migration. 

This problem keeps coming back every time I happen to restart the server! I do fishing runs and get all my books converted to different forms of protection, only when I keep them in shulker boxes within my inventory do they stay safe. Please fix it before release!

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.