Floor blocking underlay

[semi]

Does anyone know why my floor is blocking my underlay?

I'm on Floor +V01 looking up to the ceiling towards +V02

When adding a floor between +V01 and +V02 it will block my walls lying above.

view without floor:

View after drawing floor:

Section setup showing between +V02 and +V03:

Cut view is below the selected floor, looking up towards that floor.

[ToanDN]

What is the floor elevation? Play with the view range top relative to that value.

[semi]

my floor is lying just underneath the floor level I'm looking to:

I'm standing on V01 looking down starting from cut view 100. 

When I use V02 as an underlay it shows this floor but not the walls above that floor.

The walls only show when I delete the floor.