The quest to get the hunter bow, rhok'delar, is chaos at the moment and is only going to get worse as more weeks progress. The demons currently have a 3 hour respawn if killed and a 7 hour respawn if they are interfered with at all by anyone other than the hunter who engaged combat with it, which is the case over 50% of the time. The number of hunters on the quest will increase week to week, resulting in more despawns due to overcrowding and less demon kill.
I suggest lowering the spawn timer.