EP Context Surfaces: Error with sloping site

Hi I keep running into an error with my sloping site. I’ve tried it both as a closed surface and as an open surface with no holes in it. The errors say it is a non-planar surface, but it looks like the component changed it to a mesh of planar triangles.

The reason I’m trying to make it a shading component is that the hillside affects the sun path. Also tried making it a ground object, but the resulting zone was so huge that gh would just hang for hours while loading.

I also tried to make it into a mesh just to be sure, but the component only takes breps.

These are the two fatal errors I get when running the simulation:

** Severe  ** ProcessSurfaceVertices: Suspected non-planar surface:"SHDSURFACE_1133_1", Max "out of line"=9.47177E-002 at Vertex # 5

** Severe  ** CalcCoordinateTransformation: Invalid dot product, surface="Mir-SHDSURFACE_1133_1":

Here is an image of how the surface looks after being automatically converted by the context shading component:

Also a gh is attached with the internalized brep:
EP_Context_Surface-SiteError.gh (616.0 KB)

The whole gh file is here, just in case it helps too:
Office Building - Performance.gh (1.3 MB)

Thanks for the help, I’d really like to figure out how to make the terrain and hillside factor into the shading calculations.

Update: Of everything I’ve tried today, an extruding polyline is what worked, here it is:
Annotation 2020-07-16 140720

No matter how much I simplified the surface, even by means of making one from scratch, it would still give the same error. I’m thinking perhaps there is something going on where the component converts the brep to a mesh but can’t say for sure. Also tried reverse converting from a mesh back to a brep but still the same error. Here was a simplified example that failed:

If anyone knows, I’m very interested in knowing why the topo was failing. I’m thinking maybe next time a combination of independent surfaces that don’t triangulate but stay planar?