I have attempted to install Linux VMs and Windows VMs.
When creating I set 120-240GB depending on which I want at the time.
Loading the Client OS Installer, selecting the created virtual hard drive - it shows no space available or partitionable.
Vdisk.img = 56kb in size.
I believe that the VM Creation tool is not provisioning QCow or raw drives space correctly.
Image from WIn10 install post-driver installation shows the drive with zero space for easier clarity.