Sonos Arc soundbar connected to LG HDTV, in use for over two years.  Within the past two months, when I play Spotify via iPhone to the soundbar, TV comes on with still pictures portraying the music (artists, album covers), or some unrelated screen saver pictures.  Prior to ths, TV did not energize, music simply played through the sound bar using Spotify.  I am unaware of any change that I may have made.  Would someone please coach me through What to check?  TIA