Sound cutting in and out on Sonos Arc after playing Dolby Atmos content on Apple TV 4K

Sound cutting in and out on my Sonos Arc after playing Dolby Atmos content on Apple TV 4K 

I’ve had my Sonos Arc and Sub Gen 3 for about two weeks now and I’m very satisfied with the sound quality, but I’m having some very annoying issues with audio cutting in and out… 
I have the latest LG OLED TV, a LG GX (same as the CX, just wall mounted). The only two boxes I have hooked up to my TV is an Apple TV 4K and a PS4 Pro, but I’m having sound issues on my Apple TV.
Before I explain the problem, yes, I’ve pretty much done all the troubleshooting I can do. Plug everything in and out, check that the cables is properly connected, updated everything, the Arc, TV and Apple TV, everything should be up to date as I’m writing this post. 

Okay, so here’s the issue, with a half ish solution. 

My issue: 
If I play any content that supports Dolby Atmos on iTunes, Apple TV+, Netflix etc. and try to play some music through the Apple Music app or watch any video on YouTube on my Apple TV after that, the audio cuts in and out every other second. This even happens after playing a Dolby Atmos movie on iTunes and when I go back to the movie menu, the audio starts to cut in and out. It doesn't help to turn the TV and Apple TV on and off and it doesn't help to just restart the Apple TV itself. 

The half ish solution:

The only fix that I found that worked, is to play a movie that is in 5.1 after playing Dolby Atmos supported content. If I do that and then go into Apple Music or YouTube, the audio is fine and it doesn't cut in and out every other second. 

The issue: 
So it seem like the Arc might have an issue going from Dolby Atmos straight over to stereo sound. But going from Dolby Atmos to 5.1 or from 5.1 to stereo works just fine.
It work perfectly the other way around, from stereo to 5.1 or Dolby Atmos. The only thing I hear then is a little loud zippering or buzzing sound, but I guess that’s just because the Arc is switching the sound receiving signal? If that zippering / buzzing sound shouldn't happen, let me know. 

The funny part: 

Here’s the the funny part though, if I play something in Dolby Atmos on my Apple TV and after that play a YouTube video on the built-in YouTube app on the TV, the audio is fine. Same if I AirPlay music to the Arc. So I’m a little unsure if there’s something that has to be fixed from Sonos’s end or Apple’s? 

I’m seeing a lot of people on here tags @Ryan A  and @Kyle A, so I’m gonna do that too, seeing as they come up with a lot of good answers. 

If anyone else has had similar issues, let me know.