A. I recently had this problem, which was caused by a disk failure on my Hyper-V host when it started. Certain VMs wouldn't available when the system started, and that's when the Remote Desktop Virtualization Host Agent performs its scan.

To resolve this problem, make sure the VMs are all available then restart the Remote Desktop Virtualization Host Agent service using Server Manager on the Hyper-V host, as shown here.

042511-rd-virt-host-agent-small_0

Now you should be able to see all of your VMs when you create your pool.