Clip surface not working

[XtinaLngBch]

Hello! I am a new user, running 2022.  I can't figure out what's going on. I've tried dozens of changes to try to clip these 2 objects. I have a concrete slab and a landscape area that I want to carve out of the concrete (so square footage calculations are correct).  Here are the culprits:

 

Any help is greatly appreciated!

 

Thanks.

[zoomer]

For me it looks like the Polygon for the Landscape Area could be problematic.

Looks like a line is extending the Selection Highlight Border on Top.

Maybe the end of the touching Arc is overlapping the right edge a tiny bit

or such.

 

If a Polyline is self overlapping it mostly should not look ok already when

just extruded into 3D.

And for adding and subtracting 2D or 3D geometry, VW to me looks pretty

tolerant. But in CAD you can often get Problems when geometries are not

100% matching at touching borders but being slightly off.

While as long as they are largely overlapping or perfectly fitting they are save.