After creating an admin user via the API with authenticationMethod : 2 (Active Directory) and modifying that user via the API, the authenticationMethod is unexpectedly changed to 0 (SEPM authentication).
SEPM API
This issue is resolved in Symantec Endpoint Protection Manager 14.3 RU8.
Upgrading and Migrating to the Latest Release of Symantec Endpoint Protection (SEP)
CRE-13814