Missing summoning circle in Undercity

I already posted this in the Bug Report forum, but was told I'd get a faster response here:

The summoning circle in the Undercity is currently missing and as a result, I am unable to complete the Voidwalker questline. The server this is occuring on is Garrosh

Yes, I did petition a GM, but I get that "high volume of petitions" thing which means I'll be waiting a while. Figure I'd might get a faster response here.