I’ve had both an Arc and a Sonos Amp for the past few months. The Amp is hooked to floor speakers and a subwoofer, and is used primarily for my turntable. Previously, when watching TV, the Sonos app reported that the Arc was using TV audio and it allowed me to group the Amp for even more volume/bass. However today I tried to take advantage of this feature, and the Sonos app no longer signifies that the Amp is playing TV audio, and as a result I can no longer share TV audio between devices.
Has something changed with the Arc firmware, or is there some setting that might be preventing this from working?