Help using spline op (and new spline op)

I’m working on a bit of a messy patch that uses SplineMesh, I’m seeing there is a new version of it but the new one doesn’t have ‘start’ and ‘length’ and I’m animations these parameters to kinda create a chaotic version of an after effects ‘trim paths’ but in 3D space.

the existing op isn’t showing for some reason when I preview but it works in edit mode… I might have connected something up wrong but before I try to rebuild that section does anyone know if the older splineMesh op has issues? https://cables.gl/p/5fe0bbdb2cb967525479289e?s=CthpnU8Zw0aeptmY