Describe your setup. What model TV do you have? What is your Dolby Atmos source? Are you using an external media device?

It’s a Philips 4K Atmos Tv watching through sky Q, I had no problems yesterday and I’m able to watch things now with a Dolby Dig Plus output, just Atmos that has the white noise. 

Disconnect the Sky Q and Beam from the TV and unplug the Beam and TV from power for a couple of minutes. Plug the Beam and TV back in but keep the Sky Q disconnected. Run TV Setup in the Sonos app and connect the Beam to the TV’s HDMI ARC port when the app instructs you to. When the Beam is successfully connected, connect the Sky Q to the TV and test again.

Life saver. Thanks mate, worked perfectly.