After completing a nightmare dungeon, I go into a Helltide area and the area literally removes Helltide and converts to regular zone. Looking on the map only the area I am in is showing regular and the rest of the region still shows Helltide active. So I go to that area and as I enter the Helltide area shown on the map, it removes Helltide in my immediate area again. Tried logging out and back in and it does not change. I suspect it has me still flagged as being in a Nightmare dungeon as killing an NPC, it generated a blood blister that was from previous nightmare dungeon. Hope this helps.