I have been completing my protector quests (the ones with a long cooldown) and after the timer ran out on the cooldown the quest reappeared - however it had no target nor buttons to close/cancel it. Going to the guy in question (Nordain Kungar) got me another protector quest which I duly completed but the bugged one remains in my quest list with 'Available after 0 seconds' next to it.

This bugged one is 'recurring level 12 quest' while the one I just completed is 'recurring level 15 quest'. Not a big worry as gameplay-wise I've lost nothing, just got an extra quest icon really.