Touchpad horizontal scrolling doesn't seem to work

Touchpad horizontal scrolling doesn’t seem to work in Openbox.
I added the following to /etc/X11/Xorg.conf.d/40-libinput.conf (created the file)

Section "InputClass"
        Identifier "libinput touchpad catchall"
        MatchIsTouchpad "on"
        MatchDevicePath "/dev/input/event*"
        Driver "libinput"
        Option "HorizontalScrolling" "true"
EndSection

And, it is there,

$ xinput --list-props 11
Device 'Newmen Tech.,LTD 2.4G Wireless Mouse':
	Device Enabled (165):	1
	Coordinate Transformation Matrix (167):	1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000
	libinput Natural Scrolling Enabled (300):	0
	libinput Natural Scrolling Enabled Default (301):	0
	libinput Scroll Methods Available (304):	0, 0, 1
	libinput Scroll Method Enabled (305):	0, 0, 0
	libinput Scroll Method Enabled Default (306):	0, 0, 0
	libinput Button Scrolling Button (307):	2
	libinput Button Scrolling Button Default (308):	2
	libinput Middle Emulation Enabled (309):	0
	libinput Middle Emulation Enabled Default (310):	0
	libinput Accel Speed (311):	0.000000
	libinput Accel Speed Default (312):	0.000000
	libinput Accel Profiles Available (313):	1, 1
	libinput Accel Profile Enabled (314):	1, 0
	libinput Accel Profile Enabled Default (315):	1, 0
	libinput Left Handed Enabled (316):	0
	libinput Left Handed Enabled Default (317):	0
	libinput Send Events Modes Available (285):	1, 0
	libinput Send Events Mode Enabled (286):	0, 0
	libinput Send Events Mode Enabled Default (287):	0, 0
	Device Node (288):	"/dev/input/event8"
	Device Product ID (289):	4809, 4129
	libinput Drag Lock Buttons (302):	<no items>
	libinput Horizontal Scroll Enabled (303):	1

but, can’t scroll horizontally.