They frequently have issues with banks of the elevators. It's not uncommon at all to even have them shut down stand by totally, allowing FP riders only, when it gets too bad. Plus, I think the reboot process takes a long time. The good news is, if you are there when it reopens they can push a whole lot of guests through really fast so it can be great, a really short wait, for a brief period. But then it will build fast to a really long wait when those who got an anytime FP pour back in to the queue.