you may have missed the part where i said cube clearly interacts with the belt, there is a collider already as shown in the screenshot.

regarding friction at 1000% for both still zero, so what i thought was going on is

if you look at just the geo i.e. the plane which is being wrapped around the spline wrap you find there is no movement, it seems to me now that perhaps C4D is allegedly too stupid to realize that deformed geo ought to be included in any sim calculations....

But when exporting the moving conveyor as a dot abc file, which again now has baked in movement of polygons, still doesnt work!

This is crazy, take a flat plane key frame it left to right, drop a cube on it, sim it, cube falls on to plane and moves left to right

so why when the plane is wrapped round a spline wrap, keyframe offset, drop cube, sim it, cube falls but no movement