Hey There :)
Got some crashes with Apotheosis while exploring the world.

Forge 36.2.8
Apotheoisi 4.8.2
crash-2021-10-16_10.44.26-server.txt
crash-2021-10-16_10.27.10-server.txt

Cheers

Both of these would imply the structure that the second variant of the boss dungeon uses is not loaded, which would be impossible under default configuration. You likely have something else interfering.