Unmute does nothing
In order to mute the audio, it is possible to use the menu item Audio>Mute or the context menu of the application in the Dock.
Problem When clicking either of these menus again to unmute does not work. VLC stays muted.
Work around The shortcut of this menu (alt+command+) works as expected. Also clicking the speaker, left of the volume control in the inferface unmutes VLC.