Copper Citadel final boss becomes unkillable

Bug Report ID: #2694696240

As the title suggests, I was running a juiced Copper Citadel boss. I reached the boss room with no issues, but the NPC that is supposed to join you for the boss was unable to get into the room. The gate that locks out the boss room went up, trapping her outside.

The fight proceeded until the boss began his sandstorm summoning attack. Without the allied NPC to create her bubble shield against the storm, there are no safe spots to stand in so my only recourse was to portal out of the boss room before I died to the physical DoT from the storm.

The boss proceeded to never stop casting the storm, so my only option was to abandon the run.