If I had to wager a guess, the bots may have temporarily overloaded the instance servers by spamming it with queues, not unlike the great Raubahn wall of early SB. Even World Travel queues seem to get stuck at times if several people are trying to crowd into a server simultaneously (Generally because of a S rank hunt spawning), forcing you to back out and requeue to get in.

There's several dozen parties of bots per DC entering and exiting the instance at intervals of a few minutes, so I'd be surprised if it wasn't straining the server.