Curve on surface problems(or bug?)

hi:

I'm doing some work have to use "curve on surface" component

but there's a problem I can't found why..

I already check the uv points to conect curves, there have no wrong position

and some will correct connection, BUT there have some just like loose control(selected on attach file)

file is attached~

if anyone knows why and solve? is that bug?

I use 4.0sr9 & gh0.9.0012

thanks