Answer
A 200 response doesn't guarantee the specific fields you sent were actually the ones the target projection persists — some Person/Employee attributes need to go through a more specific, dedicated service (for example, one purpose-built for person data like a PersEntity-style service) rather than a more general employee-handling projection, which can silently accept the call without applying every field. If an update seems to succeed but doesn't stick, trying the equivalent call against the entity's more specific/dedicated projection is worth testing before assuming it's a permissions or caching issue.