You are unable to accept a new Duty. Please try again later.

I got booted from queue for Brayflox's Longstop, and now I can't queue for anything. The error message "You are unable to accept a new duty. Please try again later." pops up whenever I attempt to do so.

Someone in-game suggested I deselect everything from queue and wait a while, which I'm doing to no avail. Does anyone have any suggestions?

15 minute lockout timer for leaving a duty.

Cool didn't know there was a timer for leaving.

I swear I've left a Duty before and then just accepted another 1 immediately afterward. Didn't have this problem.
I've only had this happen to me once, and no matter how long I waited I still couldn't get a Duty and only got this error.

Only way I could fix it was to logout and log-in again.

I didn't -leave- a duty, however. At best you could say I might have missed a queue, but even that doesn't lock you out from being able to queue. It looks like I'll have to log-off and wrestle with the waking crowds in order to make progress past Titan today. That's somewhat disappointing. Guess I'll farm some Gladiator levels.