So these two nerds, who also happen to be my sim's colleagues, keep appearing in the apartment next door, insisting they have somewhere else to be, and then being unable to leave. Every time I reset them, they reappear. Every time I use MC to tell them to go home, they reappear. They really like hanging out there, pillow fighting while complaining that they need to leave and not being able to do it. How do I make them stop showing up?

The "apartment next door" as in within the same building as a usable living area for an actively played household but behind a Private Room Marker as a LN style apartment building would be arranged, or do you mean in a different building entirely? Do you have any apartment mods in play (Ani's or pjsutton's)? Are these colleagues residents of the town with household(s) of their own or are they homeless NPC co-workers?

Same building, unusable living area. It's an LN apartment. I don't have any apartment mods, and I think these are homeless NPCs?

I'd start by checking the markers inside that room. You will need cheats: TestingCheatsEnabled true, RestrictBuildBuyInBuildings off and BuyDebug. Even if everything is in order, I'd replace the door and the marker of the hidden room. Sometimes, for some unknown reason, they incorrectly affect those rooms that should not be affected.

I agree with Sara. The darkened out units in LN apartment buildings, each marked with Private Room Markers and a designated NPC-only door, is exactly where homeless NPC sims are supposed to go when they are pushed or told to Go Home or when they get reset. This is a substitute for them navigating off the map before going into states of hibernation when they are not called upon to do anything else. So, even if it's really for the sake of appearances, those homeless NPCs do "live" there.

What is not supposed to happen after they instantiate (materialize) out of hibernation is that they get stuck inside of those units when they try to leave them. If redoing that unit's designation with the markers and the doors doesn't help, then I would say something else is blocking them or the door is positioned in such a way that they cannot use it. Or for whatever reason it is not being seen by the game as an NPC door or it's placed the wrong way around or is locked to them. If all else fails, you could remove the NPC door, and change the room marker to Public, and/or tear down some walls, thus making what was once an NPC-only area into a Public one. The homeless sims will immediately find someplace else in which to hibernate or will revert to going of the map if there are no other such units available to them.

I did have one of my sims living in the apartment ring that doorbell to see if one of them would come out, and a third sim suddenly materialized to exit that door. So it's working kinda correctly? I finally got so fed up that I used Overwatch to perform a cruel and unethical homeless sweep of the town. I'll try replacing all the markers and the door and, and see what happens.