That looks more like a glitch with one or more of the apartment controllers than a corrupt 'hood. They are responsible for how apartment neighbours behave and when they should or shouldn't be visible.

If all else fails my Lot Cleaner (44kb) will wipe out all of the controllers so a fresh set will be made next time the lot loads.
To use it just select it in the catalogue (don't need to place it anywhere) then immediately save and exit the lot. I suggest you then remove it from your Downloads folder to prevent accidental use later.