Here's a crazy situation. 

So I own a Sony 900f and a 900e model TV. Those tvs have ARC ports in hdmi 3. So I bought a beam with surrounds and everything worked great. All of a sudden when I went to watch TV after having audio the day before, there is absolutely no audio coming through that. So I changed the motherboard on that TV and boom everything works absolutely fine. Upgraded to the ARC and after a month or so same issue happened with the HDMI 3 ARC port on that new board I put in. So go to switch out that board on the TV again with my protection plan from Best Buy where I worked as an Advanced Home Theater installer. That 900f ended up being dead in the water after replacing the board again, fine I got my money back on that TV. So I go to use my slightly older 900e series Sony, and it happened again tonight where there is no audio.

I have done every form of functionality testing you can think of. Tested out an old sound bar of mine, that didn't get audio either, reset the app and did the connect TV process cannot get a handshake from hdmi 3 in both instances that this has occurred. The only thing that works is using the optical adapter that comes with the bars and then I get my audio back. 

It seems crazy to me that both these tvs ended up having the same issue, and Sonos is sending me a new ARC to see if it's the bar itself (which I assume it would be if both my beam and my ARC have made this happen)

Sorry for the long read, but maybe someone has had a similar experience, or maybe has some insight to something I'm missing. Just seems crazy to me.