I upgraded to El Capitan and now, while the volume controls on the keyboard display the volume change onscreen, they have absolutely no effect on the actual volume. I have to manually control the volume within the app (such as QT).
Mac Pro, OS X El Capitan (10.11.3)
I'm running OS X El Capitan 10.11.3 on a mid-2010 MacBook Pro, and the volume controls on the keyboard work perfectly well, be it with iTunes or QuickTime Player.
I did a restart and reset the NVRAM. That cleared it up. I need to remember that whenever I do a major OS upgrade I need to set aside a couple of days for chasing bugs.
El Capitan keyboard volume control not working
