It's my speculation that this has become a lot more common recently, and it's kind of a hard bug to replicate, but the queue into Cyrodiil seems to be plagued by a number of persistent issues:
The most significant is that the queue will often get "stuck" for a user. This means that a player will not advance to the next queue position, but also sometimes cannot leave the queue and requeue. There isn't even a clear indication that it's happened, and usually the only way you know is by checking with friends who are also in queue to see if their queue is moving while yours is not.
When this happens, you can sometimes leave the queue and requeue; sometimes you'll have to relog because it'll get stuck on "Leaving queue..." Queuing for other campaigns doesn't usually work, but sometimes after entering another campaign you'll be able to requeue at that point.
Another issue is players can crash during their queue and have to requeue. Sometimes, it appears the crash occurs after the queue "pops" when you're trying to port into the selected campaign.
It's hard to disable add-ons as a solution to this given that it seems to impact different players at different times each with different (and some with none of their) add-ons loaded. It's probably not an add-on issue if we're being completely honest, because the server is providing your client a queue position and your queue position cannot be affected by your UI.