If the XV has lights flashing, it is receiving signal
Since it is hooked up via MIDI it has no idea what the OS is so that is a non-factor.

XV is turned down, has no patch assigned to the MIDI channels it is receiving, does not have Performance or GM Mode (whatever mode it has) turned on for multiple patch use, MIDI in is assigned to USB, or something else inside or after the XV2020 is the problem. If MIDI is getting to the XV2020 the OS and MIDI 4X4 have done their job.

Check connections from audio out of XV2020. Does it have a headphone out you can check?
Have you tried putting it in GM Mode?

I do not work here, but the benefits are still awesome
Make your sound your own!