Occasionally performing an
Update-OSMedia will generate a WARNING message that the Update Build Revision did not change.
This will also result in the creation of an OSMedia with 4 digits added to the end. This is due to there being an existing directory with the same name (which would not have happened if the UBR was changed)
The Console may show an error message if you check the Cumulative Update step
Look in the info\logs directory for *UpdateCumulative*.log and see if you can figure things out
But I tend to find the troubleshooting takes a bit of time and it may be easier to restore a previous OSMedia from my OSMedia Archive and test again. In this case that seemed to do the trick