I just thought it would be important to mention that as a different issue :] I've had this happen 2 times so far but it's every fresh start (everytime I start the game, not new game.) So that's my little addition Seperate maybe related issue as a subtitle maybe?
Edit: A fix to the Underground bug is getting a dresser and changing that persons outfit.. Might be a temporary fix but I'll let you know if anything changes. Moving out the person who was Underground and ONLY that person works, and then you can move them back, should work upon moving from Original house to house A. Not sure if moving back to Original house will help if they're still stuck underground with a plumpbob above them.