So I queued up for a game of ranked, got in, my turn to ban. The ban timer paused for a half-second, dropped straight to 12 seconds, then froze again for a few seconds and I was dropped out of the queue for "failing to lock in my ban." And, accordingly, causing me to lose my promotionals.
Understandably, it's quite frustrating. I'm not sure if it was a network error or an issue with my computer, but I'd appreciate a method to prevent it from occurring again; at any rate I won't be queuing ranked ideally until I figure out the problem.