Posted on 30 August 17 at 02:51
Hey Goka,
I just got the Head in the Clouds achievement without any issue. As soon as you finish the epilogue missions after the main campaign, you find a pivot point (I found it after fast traveling into Boston; unsure if that's the first spawn point or what it was for me). After that, they spawned for me every ten minutes in either Boston, New York, or the Frontier, and it took me about an hour and a half to track them all down. While the achievement says they might spawn in buildings or rocks, I had no issues.