STEP export creating bad object

Rhino Rhino for Windows
1

Hi

I have a surface I want to export to STEP. In Rhino, there is no bad geometry.

image
image2310×1337 279 KB

However, when exported to STEP and opened in Rhino, I get this:

image
image2649×1265 290 KB

The issue seems to be with the internal cutout. If it is removed, the export works.

And ideas what would be causing this and how to fix.

Thanks

Bad surface.stp (80.7 KB)

Bad surface.3dm (167.9 KB)

2

It appears the issue is caused by overlapping control points at two corners of the surface. You can use SetPt to fix it, and fyi.