All mobs in "The Passage" are passive (single player)

Game mode: Singleplayer
Problem: Bug
Region: europe

It is the dungeon in the swamp with a boss creature that drops a scourge stone fragment. I’ve been there twice.

1st time none of the mobs (including the boss) aggroed on me nor did they become aggressive when i attacked them.

2nd time the spiders did become aggressive when i attacked them, but the boss just let me hack it to pieces.

Steps on how to reproduce issue:

  1. Enter “The Passage”, descend into the pit at the end
  2. walk around and attack the mobs and the boss
  3. feel a bit sad about the state of affairs down there