XBOX ONE DA:I Wicked Eyes and Wicked Hearts harlequin bug.

When i progress to the point of the servants quarters and have to find the Harlequin i can find him but once i kill him he doesnt die he just starts walking around and becomes a non targetable person walking around the room like a townsfolk. When this happens the game does not recognize that he was defeated and all i can do is run around the area until my court approval is depleted at which point i restart from a previous save and have to redo the entire mission.

My party is level 23 and consists of a sword and shield Dwarf Inquisitor, Varric, Dorian, and Cassandra. Each time this has happened Dorian hit him with Spirit Mark.

Im going to attempt a run through without allowing Dorian to use that power and hope i can kill him this time.