trusts dying on first boss of The Dead Ends

Time/Frequency: I think this only stated after the 6.05 patch. I've replicated this about 5 or 6 times.
World name: Gilgamesh
Character name: Kanade Huin
Monster name: Caustic Grebuloff
Class/Level: Tank (level 90)
Party or solo: Trust dungeon
Area and coordinates: first boss of The Dead Ends

Steps:
1. Do The Dead Ends with a trust as a tank (the party members don't seem to matter, tried a combination of all of them)
2. On the first boss (Caustic Grebuloff), when it does the attack Befoulment this puts an AOE marker over each party member
3. The three NPC party members (two DPS and a healer) do not spread out enough for this mechanic and overlap each other
4. At least two if not all three of them then die because of this, which generally will cause a wipe
5. It appears to only occur when the PC is a tank. When the PC is a healer or DPS the NPC tank is far from the other 3 party members and the PC can adjust to a safe spot away from the other two non-tank NPCs