Missing top of cone shape

Evening everyone.

Been away from this for awhile and likely missed something easy, I hope.
My drawing shows a complete arch but the animation does not mill the top portion. I get either a flat top or oddly skinny above where the part should be.
Any pointers? david
workspace_naca_outer_bloc_5.kmz (158.0 KB)

you may want to use the contour op to better capture the geometry of curvature in Z

naca_outer_block_contoured.kmz (494.9 KB)

Thank you Stewart. This was a trial run of a much longer piece, I thought that running back and forth along my X axis would be the way to go. 12 feet ish.
David

if you’re sticking to planar Z cuts using outline, you need a much finer Z step downs.