I’m having this problem too, and have done for a few days now. My Guardian is level 80, not great gear but pretty much all rares and an ascended weapon.
Neither I nor my character can attack any more than I was doing. I was attacking, using signets, shouts, removing conditions off people, the lot. All I got was bronze, for like the third or fourth time in a row.
I think it came in with the patch a few days ago, but not 100% sure.