Hi Jack,

You have a lot of points bunched up on the straight line
at the base of your curve. They don't show up in MoI, but they do in Rhino
They were very close together! ( 3.45953e-008 millimeters ) (lot's of zeros!)
They're not within tolerance of the Extrude command's parameters. How did you draw that curve?


If you separate the segments and delete all the straight lines between the corner fillets
and replace them with a continuous line it will extrude correctly. Hope this helps.

Jesse