Assignment import says constituent does not exist

For the established (legacy) Volunteer Management portal. These steps differ from the newer Volunteer Management interface. Administrator controls require the appropriate school or volunteer-management permissions.

The assignment import looks up each row’s constituent_id as a school constituent external ID. A missing-constituent failure affects that row. Compare identifiers exactly, including leading zeros, and import/fix the constituent before retrying its assignment. Do not interpret a partial-row notice as failure of the whole file.