Updated March 11th, 2016
Virtualization Manager displays the operating system of a virtual machine on the VM details page.
In some cases, this information is not available for virtual machines running on a Hyper-V host. This happens when the Hyper-V Daemon is not running on the operating system of the VM. The daemon allows the hypervisor to query the name of the operating system.
all VMAN versions
Install the Hyper-V KVP Daemon.