Starting with Symantec Endpoint Encryption (SEE) version 11.0, the process for authenticating to the Preboot Authentication screen (PBA), using the Client Administrator credentials has changed.
In previous versions of SEE, Client Administrator credentials could be entered on the main login screen by selecting "Client Administrator" in the "Account type" dropdown menu.
In version 11.0 and above, the Client Administrator credentials must be entered on a separate Administrator Login screen. This screen can be accessed by pressing the "F5" button. This applies to both the BIOS and the UEFI versions of the PBA (Screenshots below).
NOTE: The color scheme may be different in some later versions, but the steps and functionality are still the same.
BIOS Preboot- Administrator Login screen
UEFI Preboot- Administrator Login screen