LDAP user download doesn't work, LDAP test does work

[oneplane]

I'm getting an odd issue where `System: Access: Users download` doesn't work (Could not connect to the LDAP server. Please check your LDAP configuration.) but `System: Access: Servers / Authentication containers` works and so does `System: Access: Tester`

The server is available and works fine, but it seems the code path for system_usermanager_import_ldap.php isn't using the same settings as the configuration or testing pages?