I have been importing a large number of contact records, for some of these records the import has failed and I receive the error message /A record was not created or updated because a duplicate of the current record already exists/.
However, when I check the source sheet there are no duplicates, in fact the sheet has minimal columns just last name and email and the email addresses are 100% unique on the source sheet. Also I have checked D365 and done a quick spot test to see if I can find any of the so called duplicate contacts (active or deactivated) by email address and there are no duplicates. I have checked the duplicate detection rules, there IS NOT a rule that says block on exact last name, there IS a rule as expected to block on contact exact email address, but as I said the email addresses are definitely unique.
Any ideas as to what is causing this?