Hi @samwoo,
I didn't think it mattered (and it MIGHT not), but could you please add "memberof" as an attribute to the Atrributes-list in the "LDAP Query"-section on the "LDAP Server"-tab.
Please keep it all lowercase (i.e. "memberof") and see what happens. IF "memberOf" (notice the camel-caps) is already listed, please remove that version (and for completeness, "memberOf" might also be tested).
Please let us know the results.