G500S and KVM

[btx926]

So, I bought a G500s -- Intended to use it thru a linkskey KVM. I only get vertical motion, though -- on both my Mac and my PC -- only up and down.. Anyone run into this before? I'm surprised it's problematic given that it's USB. I did power down every device and the KVM and start over -- still the same behavior. Mouse works fine plugged directly in. Not sure what to do....