I'm really at a stand still. This seems like it's only happening to the apartments and apartment residents up on the second floor. They keep peeing on the floor and they don't shower (even though their apartments DO have toilets, sinks, showers and proper ways to get to them) and the worst part is that I'm unable to knock on their doors. I keep getting a symbol of the doors with an X on it like so:



The number above the door isn't affecting it at all and there's nothing in front of the doors either. I'm not sure what to do? I've even widened the area in front thinking maybe the sims didn't have enough space.

EDIT: THIS DOESN'T HAPPEN WHEN THE NEIGHBOR SIMS AREN'T HOME. WTF? I can knock on their doors when they're not home, but not when they're there. And they just stand in one spot I don't understand.

Another question: Can non-player Sims not use CC or something?

You mean CC objects? Yes, they can use them. At a guess, that sounds like you have an outdated hack in your DLs folder.

Does the apartment consider the area to be apartment or community area? For example when you are playing their apartment can you swap out the chair for another one? Have you placed floor separates under fences?

You may need to stagger the doors so there not one on top of the other.

Did you use the Great Divide in any of these apartments? That often confuses the programming about what is and is not inside the apartment. Access problems can also be created by certain configurations of modular stairs.

It sounds to me like you need to go back to the drawing board on this apartment building. Take screenshots of the apartments in plan view, so we can see what you did and possibly spot errors. Apartments are tricky to build and often have to be edited several times before they work as desired.