Using SEND/RETURN on DJM-900NXS2 MACOS Driver

The MacOS driver for the NXS2 shows FX SEND and FX RETURN as channels 11/12 and 9/10. Like several other users I cannot get audio in or out of the mixer using these channels, even though they show up in my audio application.

Looking at the driver it clearly states that audio sent to 9/10 should go to the MASTER.

Can anyone help? 

@Pulse can you please comment on this. Its a feature I really want to use but no one seems to respond to any enquires.