AncientHighway, I had the same problem at one of my lots.  You could watch the neighbors showering, using the PC etc.
This was the trailerpark apartment lot.
Was actually quiet entertaining to see what they get up to, and what they find so important to do when they tell you to they 'don't feel like coming out'.  I knew it was a bug but it was hardly a showstopper

Each went back to normal darkness in turn after I managed to visit.

Ailias, did you visit these misbehaving neighbor Apartments?

OK I only just got to these, they are lovely thankyou!