I am running about 10 WS2012 on vSphere 5.1 and I do not have this problem but I have som information for you.
When you choose shutdown/reboot your RDP session closes and the server will start to shutdown/reboot but you will not see the status of the shutdown in the Console like previously on Server 2k, 2k3, 2k8 and so on.
I don't even think the message "Windows is being updated, ... ..." is shown anymore - if you choose to shutdown/reboot via RDP.
So if you want to see the status of the shutdown/reboot - Use the Console to initiate
If you want to use RDP for reboots/shutdown - Just be patient...