This keeps happening to me. Every time I click to leave a dungeon just as someone starts a role check, I leave the dungeon and when I zone back to where I was before I entered the dungeon, I’m still in queue and can’t leave the queue without logging out and then logging back in.
EDIT: To be clear, this happens when you leave a dungeon but have not yet selected your role for the role check. When you are no longer in the group and are back outside the dungeon, the role check is still showing and even selecting “no” will leave you in the queue, but not in the queue with the group. It’s a weird limbo.