I had the same issue with my 2012 rMBP, and a mate’s 2013 rMBP.
Under diagnostics, I noticed that one or two of the USB numbers were suddenly going off the rails, coinciding with the glitching starting. I’ll paste below part of what I emailed to Neural;
USBAudioOutRdWrDistance Average - When working normally this hovers around 350-400, number stays white. When the problem happens, it drops to ~170, or spikes to ~600, flashing red.
The 4 diagnostics below that one also start shooting up in number when the glitching starts - adding hundreds per second to each.
USBAudioRdWrMinNumSamples
USBAudioRdWrMaxNumSamples
USBAudioPlusOneSampleCount
USBAudioMinusOneSampleCount
I started troubleshooting with them, but I was away from home at the time/then it was christmas. When I got home, I don’t need it as an interface, so just kinda forgot about it. Last thing I heard, they recommended minimum macOS 10.14 Mojave. I was on 10.11, mate’s on 10.12.
I now have a 2021 MBP, and a Ugreen USB B to C cable. I’ve tested it for a few hours, and haven’t seen it happen yet, but it was intermittent before - sometimes working fine for several days - so there’s a chance I just haven’t tested it for long enough…