[libvirt-users] Can't shutdown/reboot Windows 10 guest if on lock screen

I am running Windows 10 vms on a Linux host with libvirt 4.0.0 and qemu 2.10.2 I can shutdown and reboot the Windows 10 guests if the no user is logged in the vm, or if the user is logged in and active/seeing the desktop. But after a while, when the lock screen kicks in (but the user is still logged in technically), the shutdown and reboot commands don't have any effect any more. Is there any way around this (except for disabling automatic screen locking on Windows)? Thank you for any hints.