Mute toggle

Anyone know how to make one button that toggles mute? I can find mute on and mute off commands but no toggle. I know it can be done as the remote roomie set up for my zone 1 has a mute toggle, but can’t really see how they did it.

What kind of device are you targeting? Roomie creates a faux mute toggle button if the device does not support a real mute toggle. Why that wouldn’t happen for other zones would depend on your device.