Chiming in with the obligatory “me too.” I had this happen about an hour ago. Apatia died early on in the fight, and I subsequently got flattened by adds and AOE. I managed to climb back up and focus down the Krait Priestess on my own, but Warden Hywel had already despawned, possibly when Apatia died. Reviving Apatia left her stuck in a “waiting” state, meaning that she would not follow me off the platform, and did not respawn with me when I tried killing myself and restarting from a checkpoint.