Settings > Sound > Advanced Settings > Match Screen and Sound > Bypass [SET TO OFF]

I had this issue where Netflix, Plex, and YouTube would cut out audio randomly for a couple seconds then come back on when using Sonos Arc on the eARC port of the LG G4 playing video from Apple TV 4K 3rd Generation.

(Name dropping the exact apps and device names in that last sentence to help people coming from google search)

I checked Sonos app while playing a movie on Netflix and I saw the 5.1 PCM as the format. Then when audio cuts out I saw the format disappear and then reappear a couple seconds after the audio returns.

I’m using a brand new 10ft Amazon Basics High Speed 48Gbps HDMI cable rated for 8K60 and 4K120 so I knew the cable wasn’t the issue.

I initially only set this setting on because I thought it would help with audio latency in console games and I didn’t turn it back off for Apple TV thinking there would be no problem.

My guess is that the TV somehow stabilizes the change of audio format or something idk. But this fixed it for me I hope this helps someone. Def my fault for messing with the settings I don’t know nothing about.