Don't know whether or not this is a bug. But During a quest where I have destroy some crystals against Devouring Earth type monsters. When I destroy the crystal it spawn massive amount of mobs, we're talking around 20+ here, the same happened to a friend I was with where he had to get parts from Clockworks, when we hit his target, a parts pile, mobs started spewing forth. Again we had like 20+ on us. Sadly I can't drop the quest as I had to drop the previous one, it was kill 5 crystals in stead of just the three I have to kill now. Its the story line from Eliza Thorpe in Talos Island.
Please help me with how I can better provide the info as I feel a write up about it is insubstantial.