In the depthRemapped tab in the AE, make sure Remap depth values is checked. Then set Maximum buffer value to 100.
I’ve found that the far clip plane seemingly behaves correctly when you set Max Buffer to 100. I don’t know why, though.
Did anyone else notice that the alpha is aliased in this pass?
FWIW, the cube is ~17 units away. I set the far clip plane to 20, so that seems about right. The top of the objects aren’t anti-aliased where the ground plane ends.