Not sure what I am not seeing. I had a longer nested string, and paired it down to a single argument, yet I am not seeing the issue:
=IFERROR(INDEX({All Stores Nexus ID Segments Segment}, MATCH([Nexus CRM ID]@row), {All Stores Nexus ID Segments CRM2}, 0), "")
The the match ref columns are the same properties.
Thanks in advance for any advise.
Mark C