I had the same problem with my Logitech g600 mouse.
I had to make xorg see the mouse as a [slave keyboard]. here is how I solved it:
$ cat /etc/X11/xorg.conf.d/10-evdev.conf
Section "InputClass" Identifier "g600 hack" Driver "evdev" MatchUSBID "046d:c24a" # from lsusb MatchIsKeyboard "true" Option "IgnoreRelativeAxes" "true" Option "IgnoreAbsoluteAxes" "true"