I think it's safe to say that everyone who PvPs knows how bad the stuck-in-combat bug has become, but in my experience the worst offender is Templar's Purifying Light skill. I've found that if I hit an enemy player with it in a big battle, whether or not they end up dying, I will spend the next 20 minutes or more stuck in combat. I suspect that the HoT that's applied to nearby allies is what's causing it, as HoTs definitely seem to be a major cause for being stuck in combat.
ZOS, for Azura's sake, please work on fixing being stuck in combat long after we've left the battle. It's my biggest frustration with this game and it's been going on for far too long.