HDMI KVM Switch Issue -- combined Keyboard & Mouse

I have tried to use a 2-port HDMI KVM switch with separate USB 2.0 hardwire keyboard and mouse inputs, but apparently combine these two separate inputs into a single USB 2.0 cable to each PC. Video works fine with both PCs, however, one of the PCs (HP DESKTOP-2IGGUAU / AMD Phenom(tm) II X4 910 [email protected] / Windows 10 Pro -- 19043.1415) will not recognize the combined keyboard + mouse input (no input response from either). Every other PC I've used works OK. Is there a combined keyboard + mouse PC driver required for this to function -- if so, I haven't been able to locate one. What am I missing? Alternatively, are there any 2-port HDMI KVM switches that maintain separate USB 2.0 channels from the keyboard and mouse, through the KVM switch, to each PC. Thanks.