We don't use DE, but I'm seeing the same problem with ePo and VSE 8.8. The server can communicate with the agent and even report properties (last comm time, VSE DAT version, etc) but it can't push policies or update the DATs.
I was finally able to get my Windows 10 (Technical Preview edition) client to communicate with ePo.
1. I upgraded ePo from 5.1.0 to 5.1.1
2. I installed the v5.0 McAfee Agent and deployed to the Win10 client
3. The client is now communicating with and reporting status to the ePo server