I recently had an issue where a number of clients were not appearing in the WSUS console even though they were being managed and receiving updates from WSUS.
This was due a number of clients having the registry value for SusClientID populated before it is deployed as part of an AMI image within Amazon Web Services EC2 and therefore a duplicate value existed.
In order to resolve the issue and remove the duplicate SuSClientID properties, I had to perform the following.
1) Stop the Windows Update Service – net stop wuauserv.
2) Browse to the following key – HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate
3) Delete the following:
Name: SusClientId Type: REG_SZ
Name: SusClientIdValidation Type: REG_BINARY
4) Start the Windows Update Service – net start wuauserv.
5) Run the resetauthorization option in combination with the detect now from the command line – wuauclt.exe /resetauthorization /detectnow.
The client should now appear in the WSUS console and in the correct computer group.
Deans Blog 