Ultrastudio 4k Mini and audio playback issues

Hi again team: so I've set my US4KM to be my system audio out for OSX and I'm getting terrible playback in the background regardless of what I'm doing, be it in Da Vinci or just transcoding files in the background.

I'll be playing something from Spotify while working, and the music will either get super chopped up digital glitch jumpy sounding, or the audio will just cut out completely. I tab over to Spotify and it's still playing. I'll go to System Prefs and select Built-in Speaker, will hear the music play fine from within the computer, then select BlackMagic Ultrastudio 4k Mini and the music will play briefly through my speakers connected to the device, but then chop up digital screamo, then cut out.

When I try playing music in itunes, the scroll bar just goes as if in fast forward and I'll get no sound whatsoever. Switching the audio in System Preferences causes all the problems to stop. But switching back to US4KM, brings all the problems back.

This little box is not exactly doing all what it advertised....... Thoughts and suggestions much appreciated!

I've also just had the US4KM disappear from my audio devices list in System Preferences -> Sound.

It's still playing via Da Vinci Resolve. And the music was playing via Spotify, then I paused it for some DaVinci playback. Went back to Spotify to hit play, US4KM disappeared from audio devices in sys prefs.

Spotify currently playing through internal computer speaker......

Many thanx for any ideas

I know this probably doesn't help, but I am also having this issue with the glitchy audio when using the UltraStudio Mini Monitor as my system audio out; it began for me when I updated to the new Desktop Video v 11.5, although I was upgrading from a much older 10 series build, downgrading to 11.4.1 didn't help.
I am running an iMac Retina 5K with Mojave, I'm wondering if you have a similiar configuration. Regardless, hopefully someone might have some insight on this issue as it's driving me nuts as well!

When you use I/O devices with Avid, Resolve, PP or whatever, they normally require and have exclusive access to the sound, at any one time. I make no judgement but I never edit/grade or tracklay and listen to Spotify at the same time. It's normal behaviour of the hardware and not a defect. BMD does not advertise multitasked audio out for the units.