Well lets start with the basics. I have no idea what a Sky Stream is, though the name scares me, because Sky.

I assume the Frame has optical output, make sure that is enabled in the TV Audio settings.

I assume you have removed the little plastic shipping lugs on both ends of the optical cable.

Cable goes from TV-optical-out to Playbar-optical in. After plugging one end into the TV, does the other end glow red? If so that means it is getting a signal from the TV.

Play something simple on the TV (by simple I mean boring stereo eg TV feed). In the Sonos app, select TV as the source.

Does audio come out anywhere (TV or Playbar)? If TV, fix the TV settings so it goes to optical. If no audio, what does the Sonos app say is playing from the TV? Could be “Silence”, “Stereo”, etc.

Thanks for the advice but this has all been done. 
 

Sonos works perfectly fine. Cable has worked previously. (Although maybe need a new one) 

feed has been changed to optical etc. 

Sky is the UK satellite TV system. 

Sorry, then what is the problem exactly?

Lets take a guess at TV audio not working.

Lets take a further guess that audio from the Sky Stream box isn’t playing. What does the Sonos app say it is getting from the TV? Silence, Unknown, Stereo, PCM etc.

What are the audio settings for the Sky box? I know Sky has a generally terrible reputation for their devices, but lets assume there are some audio options, somewhere. It needs to be set to Dolby Digital 2.0 or 5.1, and needs to NOT be set to DTS/DD+/Atmos/Pass thru or other advanced codecs.