The WinPE 4.0 build process appears to build correctly, even the Optional Components show that WMI and other components were selected to be installed, however after booting WinPE 4.0 the DAgent does not load properly. It does not show the computer name, MAC address, etc; the status might show "Client record updated" or "Unable to connect to the Deployment Server".
There are a number of possible reasons for this, here are some that Symantec Support has noticed: