I am leveling a toon in Chromie time - Cata expansion - Uldum.
Due to the time travel, I was able to fly, but could not use fast flight. As you know, in Uldum it is REALLY sunny.
Last evening I signed off and when I signed back on again everything was void dark. I could not find my quest givers and the things I needed to complete quest, and I COULD do fast flying.
Also, lots of void anomalies for me to interact with, lots of weird mobs, and lots of obelisks with red runes on them floating in the air.
I think there is a phasing glitch that is overwriting Uldum with War Within.