Anyone have an idea why Curve.PlaneAtParameter would not work on a list of polycurves with a list of matched parameters on these polycurves, when it works fine on each polycurve and matched list of parameters just fine (yes i check all of them individually). I’ve also tried point at parameter and coordinate system at parameter with the same result and also tried a codeblock. What am I missing? (I’ve made a work around, but I’m trying to understand why this doesn’t work.)