Hello! I am a newbie user of SOLIDWORKS and I am trying to design a sketch using a couple of equation driven curves. The sketch seemingly looks fine, but the extrusion fails with an error:

In the sketch you can see too 'mating' equation driven curves: epicycloid and hypocycloid, no matter what I try (even disjointing them and then selecting 'merge') the extrude does not work.

I tried Feature Check and it seemingly does not see any issue:

If I insert a line between curves, the area becomes shaded (I guess as it should be), but the extrude is still failing:
I searched as much as I could, but coming to this resource as a a last resort.

Any help would be highly appreciated