Microsoft have released the Update Rollup 2 for Windows Server 2012 Essentials. The update is available via Windows Update. More information on the issues that are resolved can be found here – http://support.microsoft.com/kb/2824160?wa=wsignin1.0
The client side package remains the same, and is automatically applied to client computers. More information on this package can be found here – http://support.microsoft.com/kb/2781268
Note that client computers may appear to be offline in the dashboard until the client side package is installed and should be rebooted after the update is applied.