All I got is, yeah sometimes an old save that hasn't been touched in a long time will be buggy. And I agree that it's probably because a lot changed in the meantime.
A lot of times this will start smoothing out after some save and reload cycles. You could try moving the household, to see if it's the lot or the household. I've had an issue with certain lots, that persisted through a few patches, and happened in different saves-- such as, Old Quarter Inn in Windenburg, the stairs up to the restrooms would stop working. Same thing happened for a while in the small dorm in UBrite. The large dorm in Foxbury has a door (to the pink bedroom) that forgets how to door, you have to enter bb.enablefreebuild then jump in and out of BB mode.
