Backup your Phases!
Today I have discovered a bug, it may be temporary, it may not. Hundreds of Gobjects in the Death Knight Start Instance in my phase have vanished. They are not visible nor can you collide with them, but they can be selected.
Try to activate or delete them and you will be hit with;
Game Object (GUID: X) not found
Again, this may be temporary, or its a case of whatever database stores the GUID's for the phases malfunctioning. I don't know how many Gobjects this has affected in my phase, so I'm going to be investigating.