I can't get my population over 12. Other settlements are over 12 and my charisma is 6 (I am not wearing power armor either). Seems like it got stuck when Preston started the castle quest and met me there but may just be coincidence.. Plenty of beds, water, food, defense etc and recruiting beacon powered and seems to be running. Any ideas?

Go to another settlement with lots of people and move 1 to sanctuary. Do it at a couple so not to take too many from one.