Moved to ePO for better support
Have you checked the orion.log for any insight? Maybe debug logging would help if you just see a generic authentication error. McAfee KnowledgeBase - How to enable debug logging and log size for Orion.log in ePolicy Orchestrator
With much embarrassment and two hours of staring at accounts on all six Windows servers and all six ePO consoles, the log led me to a typo in the username. When the senior guy set me up (I'm the new guy), he transposed two letters in my name. None of us noticed it. Log indicated that the user did not exist. Thank You.