Not enough mob spawn to complete quest

I was leveling a character through the story and got to the strand of storms where you get a quest to kill 7 sirens and 25 sailors. I fully cleared all mobs in the area and was left at 6/7 sirens and 12/25 sailors. As in not enough mobs were spawned to complete the quest. I asked in chat and another player said he saw the same thing happen about a week or two ago. It is a minor bug since you can just reset the area, but I wanted to make sure you were aware of it.