logitech mx5000 - special keys don't function anymore

I got my MX5000 keyboard working OOTB (with and without bluetooth enabled) and I had near full functionality with the special keys, most importantly the volume and mute buttons. One day, they stopped working? I tried creating a new user and logging, but not difference, so I don’t think it has anything to do with files in ~/ What else can I try? Ideas?

Would this get better response in hardware section? moderator?