The Symantec Endpoint Protection Manager allows integration with AD (Active Directory) or LDAP (Lightweight Directory Access Protocol) so that Endpoint Protection clients can be viewed and managed by AD/LDAP OUs (Organizational Units). Windows clients appear correctly in OUs imported into the SEPM, but Mac or Linux clients appear in only in the SEPM "default" group or other SEPM-defined group.
Mac computers that are AD/LDAP members may not appear correctly in SEPM imported OUs.
SEPM synchronization with AD/LDAP OUs and Mac clients was not supported until SEP version 14.3 RU1 MP1 (14.3.3580)
Upgrade to the newest version of SEP for Mac -- at least 14.3 RU1 MP1 (14.3.3580).