Including Natty I was always able to toggle (mute/unmute) the 'Master' sound volume with the

amixer sset Master toggle

command that I linked to an edge binding in CompizConfig-Manager.

Now after installing Oneiric the command only mutes the sound but doesn't unmute it. I even tried it in the Terminal but it also doesn't work. It changes 'Mono: Playback 68 [78%] [-14.25dB] [off]' to '...[on]' but the sound stays muted so that I have to unmute it via the 'sound-indicator' in the panel.

How can I get this working again? What did change since Natty? Does anyone know the command the 'sound-indicator' uses to toggle the sound volume?