Had a beam and Ones set up beautifully with a decent tv for a couple of years without any issue. This week, for no apparent reason, certain channels won’t play sound. All ITV channels for example, even ones in HD are silent. BBC fine. Netflix went silent but I’ve fixed that I think. 
 

I’ve updated the Sony tv, no change.
 

I’ve changed all available audio output channels. PCM silent. Audio 1 digital option works, audio 2 doesn’t. 

I’ve checked all cables. Fine. Music is fine. 
 

I’m utterly flummoxed. Any help gratefully received. It’s not the end of the world but the kids are annoyed. 
 

it’s a Sony 4K tv.