Please, see the file attached.
The curve is a closed polycurve with 4 curve segments.
When I try to _Project the polycurve to the planar surface, only the lower curve is projected.
Please, see the result in the file attached.
It doesn't matter where on the polycurve I click to select it.
I stay in Front view during the whole procedure.
What do I miss?
I now see, that command _Pull works.
What is the explanation for this difference?