Hi @jstruck, thank you for reaching out to the Sonos community and for letting us know about your concern. Let me help you with this. 

I would recommend to you this guide about supported Home theater audio format. I would also like to recommend connecting the Sonos Arc directly to the TV. The eARC should always be enabled if possible to get the most out of the Sonos Arc. If your TV is having trouble when eARC is enabled and you're using streaming services, you can disable the eARC from the TV settings. For 4k Bluray or any hard media plugged in directly to the TV and has Atmos, always enable eARC because eARC always looks for uncompressed audio. Here are helpful videos about it. 

https://www.youtube.com/watch?v=nLlaGs2lhIw
https://www.youtube.com/watch?v=sbTD0hqJWQQ

We can wait for suggestions and feedback from our Sonos community members, they might provide additional information about this. Please do not hesitate to reach out if you have further questions or concerns. We are always happy to help o