If you put out a scene capture cube actor in the map and set a render target to it you can see that it does not include post process in the final texture.
This is because in the official engine code the cube capture is set to capture HDR and not final scene color.
However if you override this behavior using source code modifications to use the final scene color there are very visible artifacts arising from the fact that the post process is in screen space
For example : The bloom in one face of the cubemap cuts off abruptly when the second face starts since the other face does not have the pixels that caused the bloom in the first face.
Is there a technique to get around this limitation? like deferring post process until all six faces are rendered?