Personalization upload says Person not found with unique_identifier

For GiveCampus constituent data and imports.

This upload matches an existing individual in the school using the CSV's external_id, trimmed and normalized to the school's configured identifier padding. It does not create the underlying constituent. Compare the failed row's identifier with the constituent's saved identifier and school padding, confirm the base constituent import succeeded, and retry corrected failed rows. A CRM identifier in a spreadsheet is not proof the corresponding GiveCampus constituent exists.