Preston and man escape (Fallout 4)

Preston and the original Minutemen somehow simply run away from any location in which they are sent back to the Museum. With Preston already completed all the quests, relationship with him is good, but even if to take it with him after letting him go he just RUNS back to the Museum.

Moreover, the settlers are in the same sanctuary, and imaginary Preston, there's even firing of guns (empty space turns and presses the lever).

Resetti tried - does not help.
Tried resetti AI doesn't help either.

When trying to move settlers back to itself - they immediately start to run in the direction of the Museum.

What the hell is that and how to get rid of this?

Thanks in advance!