For reasons A&H have never made clear, the xone96 Master is set to USB11/12, an annoying design decision since it makes it impossible to stream to OBS without third party software like Loopback (OBS can only see USB1/2).
You can get Rekordbox REC to recognize the xone96 but you need to change the INPUT RECORD under AUDIO in the RB preferences.
I used to own a xone96 but this was one of the ancillary reasons why we parted ways (it is a great mixer though).

as i use DVS with the 96, the record input is greyed out.