Indeed,since latest mozilla update this addon stopped working properly,for some reason sees only plugged in audio channels,non bluetooth or wireless :(
Firefox 9X has changed the behavior of the method used in this add-on. The add-on was updated to use the new method provided by Firefox 92. If you're using latest Firefox (92 or newer) it might work well after the update.
Please notice that the select button is now in the context menu (right click).
