Can't get this lofted surface to close

lofted curve.3dm (270.6 KB)
I lofted this surface between the two curves but cannot get it to cap. I am pretty new to Rhino so probably just doing something wrong.

It keeps saying that “The openings did not have closed, planar loops of edges.” but these were very simple planar curves before I lofted to them so not sure whats going on there.

Cap works on planar holes.
In the Front or Right view, zoom in on the top edge and you’ll see the hole is not planar:

Delete your surface and Zoom in on that top curve.
Select it and use the SetPt command with only Set Z checked.
Select the curve’s control points and make them all the same.
Then do the Loft again and it will Cap.

John,

Thank you!

That of course did the trick. Learned a new command.