Not sure it would help but here are parts of my .i3config:
bindsym XF86AudioRaiseVolume exec --no-startup-id pactl set-sink-volume 0 --
+10% && killall -SIGUSR1 i3status
bindsym XF86AudioLowerVolume exec --no-startup-id pactl set-sink-volume 0 --
-10% && killall -SIGUSR1 i3status
bindsym XF86AudioMute exec --no-startup-id pactl set-sink-mute 0 toggle
I can't really explain anymore how it works (forgot), but I know I tried
different ways.
What I remember: the SIGUSR part (with killall) helps refreshing the volume
display faster.
I don't know anymore what is sink. But it works for me.
