The left part of the first picture is giving an inverted circle when lying flat, but the right part of the first picture is how it should be. Same STL for both slice orientations. I tried toggling union overlapping volumes with no luck. I tried to invert face normals with Blender with no luck either.
This gives the error: The highlighted areas indicate either missing or extraneous surfaces. Fix your model and open it again into Cura.
I have tried
- manually repairing faces with Blender,
- repairing the model with Autocad Meshmixer
both without success.