dn: olcOverlay={0}memberof,olcDatabase={1}hdb,cn=config objectClass: olcOverlayConfig objectClass: olcMemberOf olcOverlay: {0}memberof olcMemberOfDangling: ignore olcMemberOfRefInt: FALSE
Not sure whether it really makes any difference, but you'd see here something like
dn: olcOverlay={0}memberof,olcDatabase={1}bdb,cn=config objectClass: olcOverlayConfig objectClass: olcMemberOf olcOverlay: {0}memberof olcMemberOfRefInt: TRUE olcMemberOfGroupOC: groupOfNames olcMemberOfMemberAD: member olcMemberOfMemberOfAD: memberOf
Don't mind about the olcMemberOfRefInt (TRUE or FALSE should not change the behavior); what's missing in your configuration is the olcMemberOfGroupOC, olcMemberOfMemberAD, olcMemberOfMemberOfAD. Probably, they are the default, but in any case they should show up in "cn=config" anyway.
In any case, no matter what your guesses are about how different versions support features, you should really check whether the problem is still present in the latest release. Only if it is your issue can be taken any seriously; otherwise, upgrading is really the only viable solution.
p.