P3421W, KVM related USB issue

Hello, I just bought a P3421W monitor and got it setup with two of my devices: one of them being a Thinkpad T14 connected via USB-C, another one being a PC connected via DP + USB upstream, on USB downstream I have wired keyboard connected to it.

The monitor worked all well for the connected device in the front, but not so well for the device on standby. When the standby device stays inactive for a while, switching the monitor to it will leave the monitor hunting for video signal and not switching the USB to that. There's a dead lock here since USB keyboard is needed to wake up the device, while the monitor won't power or transfer USB stream to the second device if there's no signal. 

I suppose it's a similar issue mentioned in post here Solved: U3818DW, USB power during sleep - Dell Community. 

Thanks!