This might have been an one time only issue. But Incase it wasn’t hope this might help. While playing on the Xbox one X. I had started a new play through after installing the 3 in 1 pack to play with the RotC. After getting out of sanctuary on. The 3rd or so minuteman quest to set up Starlight. After setting up the radio beacon, placing a few plots, and two settlers showed up, the issues started. The first to arrived started as normal, started a res. plot, then agro plot. The second just stood in the center of the settlement even when trying to command them to move. Thought was normal cause we all see those idle ones even in vanilla. Just ignored it due to another home and farm starting.
Bear with me it starts to unravel now. After setting up about 5 more home plots and 3 more farms, they would all start to begin construction even though I only had 2 settlers in the settlement. The 2nd one still stood in the center but I watched the first one basically move into new home plots and farms, only showing ownership of the set he just built. I refreshed the settlement and went questing, figuring the town would still fill but after 5 real world hours it was unchanged. Still just the 2, one in the middle and one acting normal just taking the newer plots for himself.
No one was set as a leader for the town, difficulty/involment was set to medium.
I figured I messed up on a load order, but after moving a lot around and even removing all other mods save for(and in order)
Unofficial fallout 4 patch, sim Settlements 3in1, sim Settlements year one mega pack,sim Settlements Ted’s leader pack, and scrap that settlement. Still the issue was there.
Like I said it probably was a one off bug, because I decided to just start over being I was only about twelve hours into it and was not a big lose. And it works pretty much perfectly so far about 20-30 hours in. But just giving a FYI Incase there was an issue.