Have the latest 2.3 CND files been installed on your CNS Server? These will be required in order to CNS to recognize 2.3 ePMP devices. They also add support for newly added monitoring and configuration parameters.
Be sure to install Hot Fix 1 before installing the 2.3 CND files.
Are you using Wireless Manager? If so, we have some problems discoverying epmp ,and they are been discoverted as generic devices. We have a open support ticket and they was able to reproduce the case. Has not been resolved yet. Works fine with CNS.