This is actually the third time that this has happened in the last two months. I had to start a new game the first time, the second time I realize that it was Sim settlements.I went through all of my mods 1 by 1. When I removed Sim from my mod list all of my quests was working fine. But then after some time of using Sim it did it again. What happens is when I enter an interior Cell, first my companion will not follow me inside they will stay by the original door that we entered. Then none of the quest NPC’s will interact with me, or move...they seems stuck. When I try to interact with them it says that this NPC is busy. First I had SIM settlement with the separate rise and the separate Industrial revolution. At first I thought if I remove those three and went with the Sim 3 in 1 it would work better.But it didn’t after some time it all happened Again. The only way to fix it is to remove Sim do it clean save and reinstall Sim. But after some time it happens again to the point where I might have to just completely delete Sim because it’s breaking my game.