Stuck in map boss arena (potential cause)

I thought this bug was fixed already, but guess not.
Map: Rustbowl, lvl 77

Looking at the arena, it seems like the red fog is preventing me from leaving.
I did portal out of the arena after picking up the boss loot because my inventory was full.
I believe returning to the boss arena has the game think the boss is there, so the fog wall doesn't go away.

This happened once before too, where i portal out after defeating the boss and then i got stuck in the arena

Something similar just happened to me.
Killed the boss in Steaming Springs and the red fog won't disappear.
Maybe the boss was killed too fast or in a phase, in which the games doesn't check afterwards if the red fog needs to disappear?
Portaling in and out didn't help. Needed to abandon the map.