Apologies in advance if this has already been answered, but I couldn't find anything on it..

Been running into an issue where sim #1 calls sim #2 to invite them over.  When sim #2 shows up at the apartment, the door opens, and then they immediately turn around and leave.  Is this normal or anyone else seen this happen? It makes it a bit frustrating to play when you can't invite anyone over! 

If this isn't normal behavior, I am guessing it has something to do with custom content - I dont have any hacks installed (at least not that I am aware of).  Is there a simple way to figure out what the problem is?