Hello,
So I have now dealt with this bug across 4 toons I am leveling. The key is to find a spot where you see dead bodies on ground with no blue magic circles. When a cultist appears regardless of type the circle will appear, and when you kill the cultist that appear there, the motes will appear. Just camp this spot and you will get the quest done. The spot is different per server. I found that when I logged on to my different toons to do this quest that spot had changed.
There is alot of myths about this quest, like wait till they knell etc ... wait till they perform ritual etc... you must tag them for you to see motes etc... None of these are the truth, it just appears to be.
The ritual is a circle appearing, which seems to be instant upon the NPC spawning in the location. The bug in part is that the circles don't de-spawn where npcs are once killed. So those spots you see circles that dont disappear when you kill the npc arnt the right spots.
Hopefully this helps, And I hope this bugged gets fixed before more enter game, it is a roadblock for this zone. Very very frustrating.
Edited by Drackz on 1 April 2014 12:30