While not a 100% solution I did spend time on a Dell support call and after an hour and a half of sitting on the phone while the tech IM'd back and forth with another engineer it was determined that the iDRAC licensing wasn't supported by the plugin.   We are running OME Advanced licensing whereas the plugin requirents OME Advanced +.   I didn't find this referenced in the earlier linked install/user documents in the thread but was able to find it here: [URL]   It might save some folks time if it was included in the install/config documentation that you need OME Advanced +.  While this doesn't confirm that this is the exact issue that's causing the originally reported errors, without upgrading the licensing in my scenario there's no reason to continue trying to use the plugin.
Installed the OMEVV Plugin in OME and pointed it to our vCenter environment with admin creds.  vSphere client plugin dashboard shows "Client is temporarily blocked for too many unsuccessful authentication attempt." Hosts tab thows a "vCenter with UUID XXXX-XXXX-XXXX-XXXX-XXXXXX is not registered. pop up. Pretty much everything is non-functional with the plugin. Any suggestions or insight on how to get past these errors is welcome.
OMEVV Plugin: Client is temporarily blocked for too many unsuccessful 
authentication