LDAP Management level does not remove group memberships as it should

I have a simple LDAP account with a direct group membership.

It is FullyManaged and on the management level settings "Retain groups on deferred deletion" is NOT selected.

When the account is marked for deletion and It is in deferred deletion group memberships are not removed. 

I see in LDAPAccountINLDAPGroup the membership and it is Direct and Active.

IsGroupAccount is checked and set through ITOperating data.

How is it possible that group memberships are not revoked? ...is it a bug?