I am having this same problem, and it's very frustrating.

I clicked the Banish Cerb button, it transported me to the Cerb fight zone, but then instantly teleported me back to the Light Circle Hub. I tried refreshing, but the same occurred. After a third refresh, the world loaded without showing any users and several buttons were missing. I could also no longer communicate with my guild. From there, another refresh lead to the load screen at a constant 100% load until I could no longer enter the world at all.

A fix for this would be very appreciated!

EDIT: Wasn't the maintenance to be from 12-12:30AM?