Hi Scott , had a minute to have a play , and it is fixable though this shouldn't be needed....   1.) I added 3 walls and marked them "no room definition"   2.) in Section Views I pulled the bottom of the Walls up and added a P. Solid on the slope to fill in the Bottom   3.) at the top of the stairs I deleted the Railing Wall and Doorway (Auto Stairwell?) and replaced it with an invisible wall to get the Open Below Room instead.     y