Lenovo volume and brightness keys not working on Ubuntu 18.04

Question

They worked fine in Ubuntu 17.04 and 17.10, but nothing happens in Ubuntu 18.04.

Running xev I can see the key presses are being interpreted correctly. I see XF86AudioMute, XF86AudioRaiseVolume, XF86AudioLowerVolume, XF86MonBrightnessDown, and XF86MonBrightnessUp key press and key release events. But the volume doesn't go up or down. The screen doesn't change brightness.

Possibly related, the button which switches on and off the trackpad does work, but the on-screen indicator which used to accompany it has stopped showing. (Which looked similar to the on-screen indicators for volume and brightness under previous versions of Ubuntu.)

The volume up, down, and mute keybindings in gnome-control-center are correct.

Lenovo ideapad 510S.

Update: I was using a Cairo Dock session. Things work fine in a GNOME on Xorg session.

Answer 1

I'm having the same problem on 18.04 (went straight there from 16.04), and I think it's due to Cairo Dock not playing well with Gnome settings daemon. See gnome-settings-daemon grabs multimedia keys and drops mute since upgrade 16.04.

Possibly more, relevant, details in this bug report.

Using the (g)settings keyboard to bind an appropriate command doesn't appear to work either, so I've only managed a workaround solution by enabling the compiz 'Commands' plugin (using the CompizConfig Settings Manager), grabbing the same keys (XF86AudioRaiseVolume, LowerVolume, etc.), and assigning appropriate commands, e.g. to increase audio volume

/usr/bin/pactl -- set-sink-volume 0 +5% 

(there's no visual feedback like with Gnome-shell, but the volume is changed)