Pulse audio Raspberry Os
I think that's a proof of my theory, so data rate is the problem, not a wrongly loaded audio driver.
My suggestion: Take another microSD and try this audio-optimized LE version. Chances are that it can handle your high audio data rate better than the stable LE.
I tried the suggested version today (specifically this build LibreELEC-RPi4.arm-9.80-nightly-20201230-c9e96e6.img.gz), but the audio behavior is the same. The interesting thing in both cases it that on cold boot (power up) audio works in most cases, but after reboot in the most of cases the audio does not work
Recently, when the Raspberry Os changed the sound backend from ALSA to PulseAudio, it was no longer necessary to turn off the internal sound card and everything works out of the box, even when powering the usb audio on while the OS is already running. Is there any plan to switch from ALSA to PulseAudio also in the LibreELEC in the future?