It’s not clear from your post, but If you are referring to the TV codec that’s currently playing, it’s best to scroll to the Sonos HT main product in the device list of the ‘About My Sonos’ in “Settings/System” and look at the entry next to "Audio-In”. I understand several requests have been put forward in the past to add the information to the ‘Now Playing’ screen - I give my vote to that feature too.

Thank you

Many third party Sonos apps show this right on the Now Playing screen, where it should be frankly.