I finished a Torment 12 Infernal Horde, killed Bartuc and opened the Spoils of Greater Equipment. Still, the objective didn’t complete.
Can confirm I am in T12, I had over 4000 aether, chose Bartuc and killed him then opened all chests and still had 2700+ aether left to open the obductie chest. I have a screenshot where it shows Í’m in T12 and all the boxes are opened. Screenshot doesn’t show I killed Bartuc but you’ll have to take my word for it.