What helped for me is using server.app to create the od master. First on master use server admin under service choose opendirectory but don't do anything else than selecting and save.
Then use server.app under Add Users there's a link pointing to something similar to network accounts.
That link will popup the server.app's wizard to create an od master.
Then on future replica use serveradmin to create the replica. That solved my problem.
Serveradmin messes up _ldap_replicator when creating the master. that's what i think.