I found solution which was working for me on HP Probook 450 G4: https://forums.gentoo.org/viewtopic-t-1086606-start-0.html
Concise version: make sure there is a line: options snd-hda-intel model=mute-led-gpio in /etc/modprobe.d/alsa-base.conf -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1683277 Title: Mute key LED does not work on HP notebooks To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1683277/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
