There seems to be an issue with the way that mute works when controlling the Sonos from the Sonos app or from a remote control (like my Harmony Ultimate).
When the speaker has been muted and then the volume up button is used, the Playbar is not automatically unmuted. If I click the physical volume up button on the Playbar device - it will automatically unmute. But this does not happen from the Sonos app when I increase the volume or from my Harmony remote control.
The current behavior is very "dangerous" because some people thinks the volume is turned down and keeps pressing the volume up button. But nothing happens because it is muted. But even if the device is muted - it is actually turning the volume up (I can see this in the Sonos app).
When they finally try the unmute button, the volume might be at top level and the speaker might be damaged because of the high volume.
I'm not sure if this is a bug or intentionally done like this - but I think the current behaviour is wrong. At least is it not consistent with how the physical volume buttones on the Playbar itself works