Cinema4D Exchange : spline loses points

[stefan]

I don't succeed in roundtripping a spline, created within Cinema4D.

I create a new object in C4D. There I insert a spline (Bézier or B-spline) and some 3D geometry (otherwise, I have nothing to select in the ArchiCAD 3D Window). When this is sent back to ArchiCAD, it is saved into a GDL object.

When I reopen the object in Cinema4D, the spline object and all hierachy is restored, but the points of the spline got lost in translation.

I can use the spline for a Sweep or Extrusion in Cinema4D and this polygonal geometry is visible in ArchiCAD, but back in C4D, the spline is empty and thus the related geometry is empty too.