I have two Sonos Amps, each running two ceiling speakers (front and back). In our family room for our TV watching.  Things were working fine but in the last several days suddenly the voices will fade to very low and the surround volume takes over.

It will sometimes recover if I turn the TV off and on but when I change channels it seems to trigger the effect.  Just seems odd and still learning how the app actually works.  Not sure what gas changed.