I wanted to chime in my two cents worth here as well.
Here are a couple of things for you to consider.
One is that as of one of the recent patch updates the masks that spawn during the high-level outdoor mission are going to count now. If you ask me which of the notes I read that in you're going to put me in a coma - but if it's really important to you I can go look it up again.
The second note for you is this. I did BP masks in DA as a 30 tanker and found about 9-10 spawn points that I used. They were all in fairly close proximity to each other. I started at these locations (taken from WarCry)
In Dark Astoria: Small park at Loc (355, 0, 4150), and several small spawns near the basketball courts at (4780, 0, 2525) use /loc to find your place on the map.
Once I got to these two places I started circling out farther and farther and swinging back every few mins. I never had trouble finding masks.
One thing I noticed is that if there were mobs at a given spot but no masks, I'd take out the mob and come back and there'd be a mask there. I'm not sure about this but sometimes I didn't do this and they'd respawn a bit later with masks. I just got impatient and hit the mobs anyway. If I could see a totem boss I'd skip the mob - they rarely spawned with totems in the mob - also - I never found a mask in a larger mob - usually mobs with less than 5 baddies.
Hope that helps ya.
