Hi
I have a similar issue upgrading SCCM 2012 from client version 5.00.7804.1000 to the current branch client version 5.00.8412.1307.
Also other machines their clients in the control panel "General", "Action" etc everything is showing blank and the console shows that the machines have been assigned to the correct Site Code but no client installed.
Many posts out there point to WMI issues...Have you been able to resolve this?
thanks