Captains spawning make the game crash in The End dimension

[RaeTheGit]

I'm making a modpack on 1.20.1-FORGE with very many mods (so this took quite the while to figure out as the culprit), using the mod version 3.1.1 of Mob Captains, and whenever a captain spawns in The End, the game freezes for a couple seconds and then crashes to desktop with the crash log telling "Exception in server tick loop".

I can provide the full crash log if needed.

[PuckiSilver]

It's probably the combination of Mob Captains with another mod.

In order to spawn captains, Mob Captains tags all mobs with Tags, that is a very common concept. If a mod messes with that, it may be incompatible.

Maybe the crash report has info on an entity? Otherwise, what mods do you have that could affect (only) the end? Any reworked ender dragon fight? More mobs? More biomes?

[RaeTheGit]

It's very likely it's a conflict with another mod that causes the crash. It's a very large pack as said.

What I did to reproduce the crash: Make a fresh creative world, place and eat an end cake for easy access, fly around the main island while waiting for the game to freeze for a few seconds before it crashes to desktop - as I know now because the game tries to spawn in an enderman captain.
In the overworld and nether I didn't encounter any problems like that and I believe I just remembered I've also definitely seen enderman captains spawn in the overworld during playtesting, so it's got to be something special to the End.

I've ruled out Yung's Better End Island as well as Alex's Mobs and pretty much all the performance and rendering mods as (direct) conflicts or causes for the crash, as well as Progressive Bosses, Ice & Fire and the mods that depend on them.

I've created a fresh crash log with the full modset and pasted it here

[PuckiSilver]

If you can tell me what mod it is exactly, I can maybe fix it in the future - though its highly unlikely that I will update older versions for a slight mod incompatability.