Hi Jose,
Try maintaning the parameter 2050 as YES and check once.
Kindly, also make refer to the below list of SAP notes:
1757906 - GRC 10.0 - LDAP user search does not work in NWBC
1745370 - LDAP search in GRC does not work anonymously
1718242- UAM: User search not working in Access Request.
Regards,
Neeraj Agarwal