Tonight, i used the duty finder to enter Aurum Vale. After killing the first boss, i became unable to see or target 1 member of the party (a BLM). I could see the target lines going to and from his position, and i could still see his spells going off. Also, my AOE spells (Protect & Medica) would still hit him. His blue dot wasn't showing up on the map either.

We made it to the final boss, but wiped after he got hit with Bad Breath andi was unable to heal him or use Esuna. After we restarted at the beginning, he re-appeared and the issue was solved (and i got a baby marlboro minion ).