The guards have keys to the front door on them so they don't get stuck on them trying to go outside for help. In that case they would just sit and run against closed door infinitely during testing. So to avoid that funny / bad situation, I had to give many of them keys to those doors. Other doors that require keys are not like that.
Also, look for other ways in besides the front door itself! There are multiple sneaky ways in!
Yes in the TTLG forum linked in description. I will put on here as well