How to get slab to show with stem wall foundation?

[treboralmasy1]

I am having difficulty getting the slab to show with the stem wall type foundation (second picture).
It looks okay if I turn on the display for 'Floor Surfaces' but that doesn't seem like what it should be doing.
I also noticed on the monolithic slab (last image) it does show the slab even without the 'floor surfaces' option selected.