User reports that LDAP is not functioning in 4.0.0 when using OpenLDAP, because of using attribute which is specific to AD, but not to OpenLDAP. Related commit https://github.com/igniterealtime/Openfire/commit/fb9c6a39a37461b94d9eecec559eac8b4e88d458
This page describes the commit in detail. It too lists that the change is very AD specific. http://www.doitcontractors.com/projects/0018/resolve_an_issue_with_openfire_when_some_users_are_not_seen_in_ldap_directory.htm
Pushed a fix by the original author of the change. Verified that the fix works in a LDAP-but-non-AD environment.