[Bug]: Enchanting Table initially does level 30 enchants, but then gets stuck at level 21

[Sursiq]

General Info

• [X] I didn't added any mods
• [X] I can reproduce this issue consistently in single-player
• [ ] I can reproduce this issue consistently in multi-player
• [X] I have searched for this issue previously and it was either (1) not previously reported, or (2) previously fixed and I am having the same problem.
• [ ] I am crashing and can provide my crash report(s)
• [x] I am using the latest version of the modpack

Your launcher

CurseForge

Modpack version

2.4

Describe your issue

This has happened twice now in my worlds (One solely singleplayer, the other briefly LAN multiplayer, but mostly singleplayer):

I set up an enchanting table and do a few level 30 enchants. I leave it for awhile and come back after some time to do more on different items. When I do this, the maximum level available is suddenly 21 instead.

I am unsure if this is a game mechanic or bug, but any help would be appreciated.

Steps to reproduce the issue

No response

Additional Information

The following show the initial set up and then one with extra book cases to try and fix the issue.

[Linguardium]

It looks like you built this on a chunk barrier and the wall of bookshelves is in unclaimed space. Does it work if you move it 1 block to the west or claim the chunk to the east that contains the wall of bookshelves?