Why are my settlers not doing their jobs and refusing to stay assigned?

One day I went back to my settlement and everyone was unassigned, I was fine with that, just a little glitch I have no problem reassigning 30 settlers. The problem is when I try, It says they are still unassigned. sometimes it works after 10 minutes of fiddling, but they become unassigned a minute after.

Does anyone know if this is a glitch and if there is some way to fix it? I would really appreciate it, especially, according to my save files I have played for 3 days in total.

It turns out that my cache was full and needed to empty it, it also helped to delete all my old save files.