I do not know if a similar case has already been addressed or solved in Rhino 6.
The shell of the flat face fails (a similar example is the shell of a cone).
It fails even the fillet/blend edge.
The figure was generated by a loft (I also tried to do a rebuild of the srf, but nothing …).
Check it out
Shell failed 2.3dm (163.6 KB)
I expect that the singularities (poles) in this case are making it hard to resolve the offset into a solid. Try OffsetSrf (not Shell) and see why…
If you cut back the surface inside the poles a certain distance, both Shell and Fillet edge work.
–Mitch
I understand, they are special cases and difficult to solve, but after so many versions of Rhino…
We should see if other modelers are able to run these cases, not to make unnecessary comparisons, but only to understand …
It is still unable to perform an offset or a shell of a cone, for example; It would be nice if Rhino 6 could do it …
You should see similar cases …