U4919DW, USB-C plugged message appears

I have exactly the same problem with a different monitor model, U4919DW =

Windows 10 PC - HDMI 1

Windows 10 PC - HDMI 2

Windows 10 Laptop - USB-C

When the USB-C laptop is turned off and I boot up the other two machines, I get the plugged/unplugged message until I physically unplug the cable from the USB-C laptop.

Any way of fixing this?