Consumer.write for controlling audio balance?

[georgeeipi]

I have an arduino leonardo controlloing the volume of my PC using:

Consumer.write(MEDIA_VOLUME_UP); and Consumer.write(MEDIA_VOLUME_DOWN);

But when I try the same thing with:
Consumer.write(HID_CONSUMER_BALANCE_RIGHT); and Consumer.write(HID_CONSUMER_BALANCE_LEFT);

nothing happens.
If I change the balance to, say,
Consumer.write(CONSUMER_BRIGHTNESS_UP); and Consumer.write(CONSUMER_BRIGHTNESS_DOWN);

that works, the brightness goes up and down as you would expect.
Am I missing something? Why does HID_CONSUMER_BALANCE_RIGHT and HID_CONSUMER_BALANCE_LEFT have no effect?