This was a useful pointer. I had a workflow which did all sorts of
enrichments and reconciliations, including one to Profiles. So on the
face of it a different problem. What it was doing was using a
reconciliation step to another schema. On the Reconciliation activity it
had Identification option "Identify the document from the working data"
checked and a target and join elements selected. After that I needed to
have a later reconciliation step to profiles where it's identification