I have recently met a problem that I have been receiving 0 updates on my machines that were connected to one of WSUS servers. After analysis it appeared that despite of successfull synchronization there are some problems with it. As far as I know the best solution for this is reinstalling the WSUS server.
After doing this I statring to receive an error:
Digital Signatures on file C:\Windows\SoftwareDistribution\SelfUpdate\wuident.cab are not trusted: Error 0x800b0001
As I read in the mighty powerfull internet (http://blog.jamzarwebdesign.com.au/), I have to install one update (2720211) to repair this issue.
I have downloaded this update, I opened the WSUS server on full screen, and I have noticed that in right low corner I have nitification baloon with exactly that update… I have installed it, restart the server, run on the client: wuauclt /detectnow and everything was ok