While I've read before that the garrison Highmaul missions are supposed to give you loot from one difficulty higher than what you are currently clearing, when does this come in effect? I'm currently 7/7 Normal, 6/7 heroic and 1/7 Mythic, which I assumed would give me a mythic item, or at least a heroic one. But I still get the normal 655 item chest. Has anyone else had more luck?
(Maybe this should be in raids and dungeons, but it's technically a garrison question and there's no garrison subforum.)