Tools for troubleshooting WSUS weirdness
It should work but doesn’t always. Sometimes you just scratch your head wondering why this computer didn’t get update automatically from the WSUS server as you configured. Now, there is a tool set from Microsoft TechNet that makes you troubleshoot the WSUS weirdness a bit easier.
There are 6 tools for 6 purposes in this tool set but mostly you will just need 2 to troubleshoot your problem.
Server Diagnostic Tool
The tool is designed to help administrators gather WSUS server debugging logs and configuration information for further troubleshooting.
Client Diagnostics Tool
This tool is probably the one you will be using the most. It’s a command line tool that doesn’t require you to install. Once it runs, it will conduct preliminary checks and test the communication between the WSUS server and the client machine, and will display the results in the console window.

Note that both tools are provided AS IS, so no support is available. But still, it helps you with more information from the deeper side of the problem.
WSUS Tools and Utilities [via Anything about IT]