I fired this bot up after an extremely long hiatus. Decided to test it out while farming old Cata instances. I managed to get through the entirety of Blackwing Decent, but once I got to the final fight with Onyxia and Nefarion, the rotation stopped doing anything. It didn't matter if I was targeting Ony, Nef, or one of the adds, the rotation flat out wouldn't do anything. Just stood there. This was on a frost mage at first. I tried three different class profiles, nothing worked. I switched to arcane, same thing. Just won't work.
It's ONLY this fight (so far) that is doing this. It worked just fine for the rest of the instance. I haven't tested other instances or other classes yet.