Playing through the Descent mission and get to the Heart to Heart section. I've got the Torment down to about 40% (after having been off and killed the minions) but now he's stuck. He has his head on a crystal and won't move/attack, nor can he be targeted. The minions keep spawning and I tried killing them for about 15 minutes but no joy so I had to log and can't progress. Anyone else had this?