It is not possible from wip to wip not always work the same things!
Example: In the previous wip the “extend srf” command worked on a truncated cone (the extension worked up over the vertex, in any case, it worked).
In the last wip, nothing to do, no longer works.
In prox wip will be correct, and then it will happen that nothing else will work.
But would it be possible to put some fixed points? Something certain? working?
In the end, I always try to test the usual commands that work in a discontinuous way. Going so far Rhino 6 will not be even more efficient and stable in 2020!
Mah … (small vent, excuse me).