When performing an in-place upgrade from Windows 7 to Windows 10 with multiple version of SEE 11.3 using the proper upgrade steps, post upgrade, the users no longer appeared in the UI of Symantec Endpoint Encryption.
Using the eedAdminCli --list-users command does show the users are intact, and authentication continues to function properly.
There appears to be a 3rd party security application called Imprivata, which was conflicting with Symantec Endpoint Encryption during the upgrade.
Release: SEE 11.3 GA, 11.3MP1, 11.3 HF2
Component: Drive Encryption
Workaround is to uninstalled this Imprivata security application and then perform the upgrade per the outlined steps and this allows the upgrades to succeed, and the UI displays properly.