Why does the offset surface become flat?

Basically i have this negative surface(going into -z direction) but every time i try to use the offset surface command it just creates a flat surface. If i flip it and then try to use offset surface it works perfectly.
And help and/or suggestions would be really appreciated.Question.gh (22.1 KB)

Loft is producing an “Open Brep” consisting of four surfaces instead of a single surface. They must be offset separately:

Question_2019Nov15a.gh (14.2 KB)

You should give attention to those warnings.
Your arc component failed 2 arcs: one became a line, another become a zero-length segment (3 congruent points A,B,C)

Then Loft is telling you there are problems!
See attached for a possible workaround: removing wrong “arcs” and rebuilding them.
Question_re.gh (13.7 KB)

1 Like

Thanks, i didn’t even see those.