Does the issue stop if you switch off the HDMI-CEC control on the connected device?

See this link:

https://piunikaweb.com/2019/12/04/nvidia-shield-2019-hdmi-cec-issues/

I'll test that out today and follow up. Thank you

So far this seems to have fixed it! Thanks! Now time to resolve issue #2, sound crackling. I submitted a post for that separately. This sound bar sounds very good but man it sure isn't plug and play. Seems the crackling is a common issue reported. 

I’ve not encountered that with the Arc, but have you perhaps tried powering off ALL devices (not standby) for say a minute or so. So that’s the TV, Arc and anything connected. Bring on the TV first then the Arc and then any other devices, one at a time to renegotiate their ‘handshake’ and see if that solves it. Also if using a power ‘extension’ multi-plug, look to see if changing that makes any difference too.

HTH

Well I spoke too soon. Sound is still going out and it seems to be getting worse. If we change channels in the sling app the sound will go out. Same app, just different channel. Happens randomly. 

Also turning off CEC controls is not a option. This is needed for us to be able to use our remote. Thinking about it more this shouldn't be a fix either. If that is in fact a issue then sonos needs to address that with a firmware update. 

I'm going to reach out to support and try this one more time. If we can't fix it might just return it. We've had way to many issues with this sound bar. Kind of silly honestly. It's a sound bar. It shouldn't be this complicated.  We have sound crackling sometimes and sound going out randomly. Only way to fix that issue is to cycle audio sources.