Interlude act 2 The Khari Crossing boss fight bugged

I've run into a major issue with the scorpion/worm boss fight in the Khari Crossing.
I've tried twice now to kill them, and I do succeed, but they do not drop any loot nor can I leave the arena, not by walking nor teleporting.
I can respawn at checkpoint but that cause the fight to restart.

I'm playing a mercenary/witchhunter and kill the scorpion first if that matters.

same happen to me