Hey Rod,
Sorry for the delayed response, what does the sign say when you enter the game before it messes up?
it says closed. When i turn it to open, the door stays in the same position.
I do have a suggestion or two which can serve as a solution.
Have the shop sign become independent. For example, set the sign on the wall next to the door instead of on the door and have the door itself open and close freely regardless if the shops open or not.
Second suggestion would be to give the NPC's the ability to either open the door, or clip through it. This can also help prevent them from getting stuck on obstacles since that tends to happen often aswell.