A blank manager reference can be valid or defective. The chief executive is the root of this fictional worker hierarchy and has no manager. An active operations analyst with no manager needs review. Keep that exception rule in the report rather than telling a reviewer to ignore a row after every export.
A populated ID also needs a valid relationship. Looking up the manager's name or status can expose a reference that doesn't resolve, and a terminated manager may require a separate check. Start from active workers when the question concerns current reporting relationships. Keep stable worker IDs, organization and the raw manager reference beside derived flags. This gives the HR partner enough evidence to investigate without treating the report itself as permission to alter a worker record.