U3818DW, USB Upstream bootup

I have my U3818DW set up with an old desktop using an upstream cable with my keyboard and mouse plugged into the monitor for KVM usage. Any time my computer restarts, it will say there is no OS detected as if it was trying to boot from the monitor's USB hub. If I unplug the upstream cable, it says no keyboard is detected. For now, anytime I restart, I have to unplug the upstream cable and move the keyboard USB over to the desktop until Windows boots. I've tried removing anything USB related from the BIOS, but still no luck. Anyone have any ideas? My knowledge of computers is pretty rudimentary.