This has happened a couple of times now, I'm not sure what triggers it.
I have only seen this (I think?) on random.
The sequence of actions and events goes like this:
1. I queue for a random vet.
2. Prompt comes up (at some point) to accept the ready check. I do so.
3. "Dungeon Finder Queued" disappears from the tracker at the side, and the "Notifications" icon on my chat window lights up.
4. I open the notifications window and there's the finder ready check there even though I've accepted it. Clicking the tick or cross does absolutely nothing.
5. This stays there forever: can't queue, can't remove the notification. I have to log out and back in to clear it.
This is particularly frustrating on a DPS toon where queue waits are anything up an hour currently... or up to two hours when this happens.
/d