Delirium issue - Boss area

Hi,
Always having that issue, the delirious mobs are always not "touchable" while they are in the boss area and I am not.
However, they tend to block the entrance and are invicible unless I manage to "roll in" the map boss area without getting killed.
Please, fix the game, thank you.
Regards

Update:
Not only delirious mobs but also the Breach and Corrupted mobs are kind of protected if in the boss area while you are out.