BootGuard not accepting password

On building a new laptop I install client 10.3.2 MP1 set an admin passphrase and encrypt the drive. On reboot you enter the admin passphrase and then log in with an AD account. The desktop client the enrols the user account with the encryption server. All fine so far.

Then when I reboot the BootGuard login screen will not accept the known good user account password only the admin passphrase. This has just started this week worked fine before nothing has changed on the encryption server.

I hve tried with different hardware platforms and different build images. The encryption client is installed sepereratly after the build process has been completed.

Can anyone assist?

Thanks in advance.