This was the log situation with our customer while building a new reference image with SCCM:
The client is busy downloading updates from the Deployment Point and putting it in the Ccmcache folder.
But for some reason, the activity in WUAHandler.log suddenly stops with the following lines:
Successfully completed scan. WUAHandler 09-Mar-16 14:00:53 3016 (0x0BC8)
Going to search using WSUS update source. WUAHandler 09-Mar-16 14:02:06 2668 (0x0A6C)
Synchronous searching of all updates started... WUAHandler 09-Mar-16 14:02:06 2668 (0x0A6C)
Usually, after these lines we would expect lines were it is doing the
actual installation of updates which it doesn't.
It seems we are not the only ones dealing with this problem. MS created a new solution for people like us dealing with these types of issues.
They created a so-called "Convenience rollup update for Windows 7 SP1"
You find more informations about this here: https://blogs.technet.microsoft.com/windowsitpro/2016/05/17/simplifying-updates-for-windows-7-and-8-1/
And the corresponding KB article is found here: https://support.microsoft.com/en-us/kb/3125574
This Convenience rollup does not include updates that are not broadly available and necessary and also not updates they introduce behaviour changes or hotfixes they need additional changes like registry keys etc. So it will shortcut the whole process dramatically but there are still other updates you need to apply additionally.
