Audio input via USB C drops after an hour

I'm running a mirrorless camera with mic to an HDMI switcher and output that to an M2 Mac Mini running Sequoia, via USB C. I'm able to monitor the switcher on a seperate monitor where I can see both audio and video signals. No issues there. The Mac, tested using multiple software - OSB, Zoom et al – never lose the video signal, but after an hour or so, the audio vanishes. I've swapped USB cables, and tried various inputs to the Mac. Swapping to a different input and back doesn't do anything, restarting devices does fix as does unplugging and replacing the USB cable. Obviously both are unsustainable during a broadcast.

As this happens only after an hour, I'm not suspecting hardware as I would think that would just not work. Any thoughts on drivers/buffers/ etc that can be reset to clear or clean the audio path?