I also had this problem, but I came in from the east and found the bodies that you needed to find before finding the demon. Once I broke the ice pillar thingies, I never got the cutscene afterwards. It still had the little quest marker telling me that I had finished dealing with the demon, but there was absolutely nothing there. No demon or anything I could loot. So since I didn't get a cut scene, I walked away and came back and the demon was back but there were no pillars and it was attacking us! I've done a lot of research and no one has had my problem. Anyone know what I can do to get rid of this??