Do you have the Arc plugged in to the TV’s ARC port? Is CEC turned on? What make and model of TV is it?

Another generic thing, have you rebooted the TV by unplugging it from the wall for 5 minutes? Oh, and have you checked for updates to the TV set?

Yes the Arc is plugged in to the TV's Arc port and the CEC is turned on (both are always like this)

TV is a Panasonic TX-65JX850B 65" smart TV.

I did check for updates but no software update was available as it said that the latest update was already installed.

I did, however, do as you advised and unplugged the TV for 5 minutes and after a short wait, the Sonos Arc recalibrated itself and everything is working again.

Thanks for your help, I should have turned the TV off before asking for help but I will try this in future if the problem reoccurs in the future.

Cheers  

Is Autoplay enabled for the TV input?

Sorry, I don't know what you mean.

I have never had this problem before and I have had the TV for over 12 months.

HI. Are you referring to this on the Sonos app itself?

If so I have always had it , (TV Autoplay) off so I assume I should switch it on to avoid this problem happening again?

Cheers  

I just googled it and have decided to switch the setting on.

It seems strange that it is off by default !

It’s been a while but I believe you have the ability to set autoplay during the initial setup process.  It seems to be fairly common that people didn’t turn it on and are unaware of the setting.

Yeah you are probably right, I don't remember setting this up on initial installation!

Thanks.