Longfellow stucks while Walk in the Park quest. It`s a main dlc quest. He just staying in front of Child of Atom NPC who should start dialogue with him in the middle of a cliff is a way to Acadia.
I tried to roll back to older save but situation has repeat.
When i teleporting NPCs closer to each other by using console command `moveto player` dialogue still not starts so i think it`s not a movement bug
Sorry for my english i`m no native