Describe the bug
Mobs with the PersistenceRequired tag are despawning with this mod.

To Reproduce
Spawn a mob with the PersistenceRequired nbt tag set to true. I'm not sure under what case or scenario that triggers the mob to despawn but I'm assuming traveling several blocks away.

Expected behavior
Any entity with PersistenceRequired would not be despawned

Thanks for the report. This and some other issues are fixed with version 11.x and higher.