Have the same problem but only when I use the StudioLive 32 as the primary audio interface for the computer and watch "YouTube". When I power it off and on, it returns. You can also try this, it works sometimes: Open up Terminal, copy and paste this "sudo pkill coreaudiod", without the quotations and hit enter. Enter your password and Coreaudio will be reset.
When I use it only for any of my DAWs, it never happens.
When I use my Focusrite as the main computer audio interface and use the StudioLive 32 as a line mixer it never happens. Even if it is still connected to USB.
Conclusion: It is an USB issue. USB audio has always been stable and other devices in the system, especially when online, can interfere with the connection. Don't use your StudioLive as the main audio interface for your computer, only use it in DAW mode. Get a cheap 2ch interface for the computers audio :).
Hope this helps someone !!