Normally I’d suggest generating a diagnostic report and see what that shows for Sonos support. Unfortunately a factory reset will delete any info that might have helped. However, it may be worth doing, in case it reveals anything. 
Also, have you tried powering off your Beam, and then restarting your router before powering up the Beam again?

Can you stream music to the Beam? Is it just the tv sound you’re lacking? If so, the tv may well have received an update. Try unplugging it from power for 30 seconds before restarting it. 

Phone up Sonos support and had my issue fixed.  Thanks for responding to this conversation. 

Could you explain how the issue was fixed, so others can benefit as well, please?

For some reasons the mobile app - autoplay feature was turned off.  Toggle that back got it working. Adding to that, I replace the hdmi cable with a new one but to the wrong port.  Sonos support reminded me Philips TV uses hdmi-2 for ARC.  These steps solved the problem. 

Awesome, thanks. 

I try to recommend to people to double check many of those settings, even if they haven’t touched them before. My working assumption is that there’s a potential surge in the power that messes with the software in some way, but that’s a guess. It certainly doesn’t hurt to double check, no matter what. 

Happy you were able to resolve your particular issue!