I monitor my audio via a USB Behringer mixer.   If I roll playback backwards or lift edit, almost every time the audio through the USB goes silent, then reappears on the Display speakers, then goes silent again and then pops back to the USB output.   This is not a smooth thing, it's very random but very frequent, and playback can happen in silence for a second or two that cannot be stopped while it figures itself out.   After this has happened a few times, I can exopect a crash.   What can I do about this?

The problem turned out to be the USB audio output into Behringer mixer.   Once I switched to Display Audio, the problem went away.   Disappointing that USB audio is not supported, as it's been my way of routing audio to my mixer for almost 20 years, but there you go.

Not sure if I can help, but I have been using Media Composer with USB audio for a long time. My current setup is a iMac Pro with USB audio output to a Mackie ProFX12v3 mixer. To get it to work in MacOS, I have to go to Audio MIDI Setup, select "ProFX" from the device list, then I'm given input and output options including the bit depth and sample rate. Perhaps if you go there and change the settings to a lower bit rate, or similar, and then see if it works better. In Avid I also have to change the audio output settings because I use A3 and A4 on the Mackie mixer instead of the default A1 and A2.

So in my experience, if you can play sound from the Mac (iTunes, for example) then Avid should work (assuming stereo output).

For the record, in case it helps someone else, my settings are:

Audio MIDI Setup:

• Device: ProFX (2 ins/4 outs) [Mackie Mixer]
  
• Input: Format 48,000 Hz, 2 ch 24-bit integer, Master stream (mixer to Mac) volume 0.377; Analog 1 & 2 volume 0 (I'm not capturing audio, just monitoring)
• Output: Format 4 ch 24-bit Integer 48.0 kHz, all volume sliders set to max 1.0
• Configure Speakers: Configuration: Stereo, Left: Analog 3, Right: Analog 4

• Output tab, Stereo, Mix to 3-4
• I have to set this for each new project as it defaults back to 1-2