I just switched from the last stable version to new experimental version (v 2.760).
I noticed that whenever I pressed the microphone mute button, the microphone volume was correctly set to 0, but the icon was not changing. In the stable version, the icon was turning red as expected.
I managed to fix that by replacing the
return " "
in the applescript by
Now everything seems to be working fine.
I don't know if those return " " were intended or not...
Anyway, thank you very much for your work @GoldenChaos.