I’ve seen posts about this bug since February this year, but I am making a post with my own findings (as well as reporting it in-game).
In Outland’s version of Shadowmoon Valley, there’s a persistent bug that locks you in combat if you fight a mob or just approach too close. Insofar the only effective methods of breaking free were to leave the zone entirely, or die; and even then it has to be your health reduced to zero. Jumping off the side into the void doesn’t clear the status. If you have pets or minions, they also have to die, or else you’ll be in combat as a ghost, and still in it when you revive at your corpse. Alt + F4 and Hearthstoning also don’t seem to clear it, unless your HS takes you to another zone entirely, as it counts as leaving SMV, I guess.
The bug only started happening once I picked up the quest “Harbingers of Shadowmoon” from Zorus the Judicator in Wildhammer Stronghold. You have to don quest-given goggles to see neutral-yellow ghosts around camp, and fight 12 of them. Once done, I noticed I couldn’t re-equip my normal helmet as I was in combat, even though no ghosts were aggro’d on me any more. Later stages of the questline also give you goggles to see specific ghosts, but they won’t work in the Stronghold anymore - I went back to see if there was some ghost stuck in aggro state, to no avail.
I came in with a high-level Horde character to see if the Horde-side equivalent of the quest will do the same, but the bug didn’t occur, so it might have been just completely random. I’m hoping it won’t come out on this character as well, because it’s quite the hindrance in getting Loremaster completion. Regardless, seeing how long people have been getting this bug, seeing it fixed would be nice.
P.S.: Forgot to add, but the whole process of cache clearing and AddOn-disabling yielded no results neither.