For some reason random instances set themselves to normal even though my raid and dungeon difficulties are set to heroic. I went to run Mogu’shan vaults and didn’t realize until partway through that it was in normal even though I’d been set to heroic. Same for Sha of Fear. My friend has been having this happen to them with dragon’s soul too, even though they are set to heroic in raid difficulty.
This can happen after entering an instance which doesn’t have any difficulty but Normal. Internally the system has to switch back to Normal to let you enter, but the client-side UI doesn’t reflect this change - nor does it always re-apply your chosen settings after leaving. It’s been better since 10.2, but still not great.
It’s even possible doing this to enter some kind of weird limbo state where your UI shows you with no difficulty selected (and no size for raids). For me this usually counts as 10-man Heroic raid and Normal dungeon, though really it can be anything.
Only solution I’ve found is to make sure to re-select your chosen difficulty and size after leaving any fixed-state zone.
I seee, that makes a lot of sense. Thank you for the explanation