Cannot unmute

[boxofrox]

Once a channel is muted, sliding the volume bar has no effect.

1. Add a channel.
2. Activate a few beat buttons to hear some sound.
3. Mute the channel.
4. Slide volume to max. Note the active beat buttons generate no sound.
5. Flip another beat button (on or off). Note that the volume slider jumps back to mute.

Verified in Chrome. Couldn't get sound to work in Firefox.