I upgraded ePO 4.6.4 to 5.1 and supposedly as per KB79169, EEFF extension 164 is supported. In my case it was not. I had a hit and miss when trying to access EEFF policies and at one point there was no EEFF Keys "button" in the console. Also I discovered this precisely because a new workstation was not retrieving the key as you describe in your issue. It turns out that extension 168 corrected the strange behavior I was experiencing in 5.1.
At the very least have a backup of everything as per the disaster recovery documentation as precaution before upgrading to this extension, or contact support for further assistance.
Message was edited by: eeffuser on 3/10/14 9:37:53 PM CDT