I'm having some issues granting permissions to AD users in ovirt-engine 4.1.  Users can log in but receive an error as below.

The user user@example.com@example.com is not authorized to perform login

I am also not able to grant this user any permissions through the admin console.  Entering a user name in the search field for the System Permissions section results in a blank list.  Attached is a screenshot for reference.

Does anybody have an idea on what would cause this?  The log files aren't very useful and don't show any errors.