Pulled him to poop mountain. He gated, summoned tank. We went down and attacked him again. Except for our inadaquete push, he was not moved from his spawn when he chain gated.

Perhaps the bug is -- If the NPC gates once (away from spawn point) they are allowed multiple other gates no matter the distance (on the spawn point)?

Kinda what it sounds like, fight him on spawn I guess and see if he tries to gate.