Bulk Export 400 on Legal Hold Metadata Filter

Anyone free to help troubleshoot this bulk export failure. environment: genesys cloud byoc eu-west-1. endpoint: post /api/v2/bulkexports/exportjobs. filter: legal_hold_status for compliance audit trails. the api returns 400 bad request. chain of custody metadata is required for legal discovery. any ideas why the filter fails?

{ "code": "bad_request", "message": "Invalid filter syntax" }