My old Dell has (3) separate buttons for volume control (mute toggle, lower, raise). Mute did work, but the other two didn’t.
In ~/.config/sxhkd/sxhkdrc
commented this out
# # Raise volume
# XF86AudioRaiseVolume
# amixer -q set Master 5%+ unmute
# # Lower volume
# XF86AudioLowerVolume
# amixer -q set Master 5%- unmute
and added this
# Raise / lower volume
XF86Audio{Raise,Lower}Volume
amixer -D pulse sset Master {5%+,5%-} unmute
After save and sxhkd reload all the buttons work