Try this:

Disconnect everything from the TV and unplug the Beam and TV from power for a couple of minutes. Plug everything back in but keep everything disconnected. Make sure Bravia Sync is enabled in the TV settings. Run TV Setup in the Sonos app and follow the app instructions. When the app instructs you, connect the Beam to the TV’s HDMI ARC port using the Sonos-supplied HDMI cable. After the Beam has been successfully connected, connect your other devices to the TV.

Thanks , will give it a go and let you know 

Hi have tried the above but too no avail, I’ve got Sony tech doing a call back on Tuesday, fingers crossed they can sort it , hoping I’m not gonna have to replace tv 🥴

It does sound like it’s the TV CEC (‘Bravia Sync’) protocol perhaps not working as it should be - particularly as the Beam did work okay with the Samsung TV that you tested. Let’s hope the Sony tech staff can sort it for you.

Searching online, I did find these two suggestions to fix some Sony TV models with connected Sonos products. So here they are for your info. (Just in case it ‘perhaps’ may help you with your TV). Maybe have a play with the settings mentioned and see what happens…

Fixes for some Sony TV’s 

Turning on IP Simple Control
Open Settings
Go to Network and Internet
Go to Home network
Go to IP control
Go to Simple IP control
Toggle On 

https://youtu.be/VXDYspxEClg

Setting  RS232C Control to "Via Serial Port"
Open Settings
Go to Remotes and Accessories
Go to RS232C Control
Set it to "Via Serial Port" 

https://youtu.be/StZc22GENe8

Thanks Ken , tried the above but didn’t work 🥴

Here’s hoping then that the Sony tech staff are able to sort it for you on Tuesday.

Turns out that was Sony customer support, they have now escalated my case too Sony technical awaiting another call back… you can’t make this s**t up 🤬