After killing the Infernal Attackers that spawn around Shadowmoon Village, I found I was stuck in combat. Leaving the area didn’t fix it, neither did fighting other things, or visiting an inn. I had to get killed to clear the status. While questing I got close to one - but didn’t attack it, or aggro it - and got stuck in combat again. This time I caved and used my hearthstone, which cleared combat status.
Edit: Changed hearth location to the Inn in Shadowmoon Village in case it happened again. Upon hearthing back to the Inn due to being stuck in combat, I found that I was still stuck in combat.
Edit 2: I had to exit the zone to Terrokar Forest to clear Combat status without killing myself.
Edit 3: Problem seems to be spreading. The Demons around Legion Hold, and the wildlife (Felboar and such) are doing it as well now.
Edit 4: Issue did not exist in Terrokar. I guess that means I’m moving out of Shadowmoon for now.