Hello! In what projection do you want to create the Y-axis spline? The documentation says "It is not necessary to align the Y spline in 3D space. Just create it on any XY plane, RailClone gets the origin and extent of the spline automatically, using the local X/Y vertex positions. Z is ignored.".
I am creating a spline in front view and I have this.
If I convert Y Spline to X / Y everything works. But in the lesson, everything is defaulted