I was going to suggest isolating the offender in a bedroom or spare room behind a locked screen door. I know that sounds silly and it may not be an option since you are putting your house on the market, but it does work. They can still see what is going on around them, but can't get out. Screen doors can be bought inexpensively, if you get a wooden one. I think screen doors or gates are much better ways of isolating a dog or cat (of course, gates don't work for cats) than closing doors.

I wish you luck. Wish I had more ideas for you.

Logan