Good Evening,
Here is the list of limits of the vcsa in 5.5 VMware vCenter Server Appliance 5.5 (vCSA) Limitations | Virten.net I think the more global question is why don't the plug in work... well I think this is whole transition to web client. We can expect to see more plugins in the next 6 months as VMware forces all the partners on to web only client. Once we see update manager we know and end is in sight.
Thanks,
J