I don't have a QMK device to with, but from a quick look at the source code it looks like you could build QMK without MOUSE_ENABLE defined and flash that firmw

I don't have a QMK device to with, but from a quick look at the source code it looks like you could build QMK without MOUSE_ENABLE defined and flash that firmware to your keyboard to workaround the problem with your KVM. I would also consider opening an issue I would not be at all suprised if the devs have a better idea for how to deal with your quirky KVM