One of our clients had an issue with Data Import, where while trying to import data an error was getting displayed – "The Records were not updated because the following Microsoft Dynamics 365 fields were not found: <field name>". This was a bit strange as the field was right there in the Header on the form.
After investigating, I found this was happening because there were two fields with the same display name.
After renaming the field display name and publishing it, I was able to successfully import the data.