I have an assebly with the door going down to grade level and the flanking windows 30 inches up. I used a profile to create the assebly shape. In plan you cannot see the brick below though you can see it between the assemblies I have attached a screen grab.
I couldn't get it to work, I changed the cut plane in both the dwa and the wall to no avail. eventually broke it into two dwas and a door
The display of the DWA's can be very cantankerous.
I have some that display a sill at a door opening and whatever I try, I can't get it to turn off.
And on others I don't have this problem and the door opening shows correctly without a sill.
Go figure............
Sometimes I get so frustrated I just draw 2d linework.