WFM API 409 Conflict during bulk schedule publish

Has anyone figured out why the POST /api/v2/wfm/schedule/publish endpoint returns a 409 Conflict when pushing weekly schedules for our Chicago team? The payload is valid JSON, but the response indicates a version mismatch despite using the latest etag from the initial fetch. This blocks our standard Friday 5 PM CDT publish window.

{ "errorCode": "SCHEDULE_VERSION_CONFLICT", "message": "Resource version mismatch." }

Is there a known race condition in the Genesys Cloud v2 WFM API?