When you use the 'Find Computers' feature in the Enterprise Console to show computers on your network, some may appear in the 'Unassigned' group with no operating system listed.
When Enterprise Console finds computers, it checks the Windows master browse list. If the computer is present in the browse list but cannot be contacted, its name appears in the 'Unassigned' group but no details (such as operating system) are displayed.
This can happen if the computer has been recently turned off or disconnected from the network, and the 'Find Computers' wizard is run before the browse list has been updated.
What to do
Ensure that the computers you need to protect are switched on and connected to the network. You must also ensure that they meet the minimum requirements for remote deployment. When the browse list is refreshed, the computers are redisplayed with their operating systems listed.