For some reason unknown to me Rhino is drawing geometry that is below when using a plane. My plane is way above the under geometry.
Edit: apparently this is also happening with Rhinos Make2D, changed tags.
It looks like the curve gets assigned as not intersecting with plane, and thus is completely projected, when it is entirely occluded by the geometry on top…
Note the layers:
Problem is sometimes this below geometry is visible from the top, Make2D should just keep the visible portion and trim the rest.
This specially important in architecture when you want to have a plan (thus the clipping plane) while still seeing the projection of the below geometry. Which in most cases represent terraces.