Maybe try power-cycling both Arc & TV - use the HDMI cable that came with the Arc and perhaps toggle the TV HDMI-CEC off/on, before running the TV Setup again in the Arc room settings in the Sonos App. Hope that works for you. If no joy, try it again with eARC switched ‘off’ in the TV settings.

Use the cable that came with the Arc. Do you have any other devices connected to the TV? Is CEC enabled on the TV?

Tried changing hdmi cables, restarted both, removed play station hdmi connection, switched on/off cec and earc,… runic out of ideas here. Its confusing that it is recognised by the tv.

It worked. Just went through everything again. Might have been problem with interference with playstation. 

@Mladen Try this:

Disconnect everything from the TV and unplug the TV and Arc from power for two minutes. Plug everything back in but keep everything disconnected. Make sure CEC is enabled on the TV. Run TV Setup in the Sonos app. When the app instructs you to, connect the Arc to the TV’s eARC port (probably HDMI 1) using the Sonos-supplied HDMI cable. After the Arc has been successfully connected, connect the PS4 to the TV.

My tv used to work flawlessly with my Sonos beam 2. I have to turn off my tv to move to another room and now Sonos beam 2 Is not working with TV audio. Only works with my cellphone audio. I am using exactly the same arc port on tv and the original HDMI cable that just what came originally with Sonos box.

Try unplugging both the TV and the Sonos from the wall for 5 minutes. Plug the TV back in first, and double check the audio settings, which possibly were changed. Also, check for a firmware update on the TV. Finally, plug back in the Sonos.

Do not do a factory reset of the Sonos. 

Oh, I’d also suggest you double check the HDMI cable connected to the Sonos was properly plugged in to the ARC port in the TV set. Might be worth reseating both ends of that cable, too.