Due to the age of my AVR and TV, I have the following config
Odroid N2 > HDMI > Splitter
Splitter output 1 > HDMI > TV (4K)
Splitter output 2 > HDMI > AVR
This was working fine 'til I upgrade to CE 20.1
First, I had to generate disp_cap file as CE could not get the TV capabilities (I guess) and max resolution was 1080 when playing 4k video.
Now for almost all 4k video, my AVR doesn’t get the audio signal. When playing 1080 all is good.
I can’t really get why some are playing well with audio, maybe lower video debit rate.
You still didn’t upload any logs for non-working version.
Did you try to check on fresh 20.1 install without restored backup?
Also check that audio output is selected correctly
See attention blocks more detailed in link below: https://wiki.coreelec.org/coreelec:audio