How do you render out the background object and use it in after effects with multipass layers

Basically, i'm rendering my scene where the objects are on a plane with a white reflective material.
I have used the same material on a Background object.

When I render my scene using various multipass options and the open the compositing file created in after effects. My objects are there correctly on the plane, but there is no background object?

I.e it appears the cinema 4d background object doesnt get rendered out?

Its there in the RGB pass, but not in any of the other passes.

So I tried to do a render with alpha turned on, but then the alpha channel didnt show anything? So its like the alpha sees the background object. So then I tried an object buffer on the background object, but it too came up empty?

So i'm trying to work out, how I can get the background out of cinema 4d, so i can composite it into after effects with my objects.

Any help is most appreciated