I have 2 quests that I need to turn in to Preston Garvey. "Ghoul Problem at Greentop Nursery" and "The Lost Patrol." When I go up to him to talk, he responds with "We need to focus on taking the castle back." Both of these quests are done and the next step is to speak with him. I have tried sleeping for 5+ days, killed him a few times, reloaded. Nothing seems to work. Has anyone else come across this or know how to get around it?