I can't seem to make a utility room under these stairs. It may be that there is something unique to the plan that is causing a problem when I try to build the walls. This flight of stairs is done in five different sections, it's a bit messy and tedious to rebuild, and knowing how difficult this will be to build, I need to hide a lot of the structure inside a utility room. There is a balcony above (open below) in this area, and there is a bit of an odd overhead obstacle that seems to confuse Chief over by the 2nd and 3rd tread. I've got a sink and some furnishings below the highest part of the stairs. Moving them didn't help. Moving my walls below the stairs in a 100 different places didn't help.
Here is the problem shown in 3D view (see attached file). You can see where the room has been drawn because the floor is different. The door for the utility room is the only part visible. Building walls at different places around stair tread #3, 4, 5, etc. didn't work. See also the 2D view. The plan was uploaded, too. Two Story Idea L (Stairs-test).plan
You guys are amazing, so I thought someone could give me some pointers.
Chief Architect Premier X5, Windows 8.1, i7 with 8 GB