PATCH /api/v2/conversations/calls/{id} transfer to queue failing with 400

Trying to programmatically transfer an active call to a different queue via the Conversations API. The docs say a PATCH to /api/v2/conversations/calls/{callId} with a queueId in the body should handle this.

I’m sending this JSON payload:

{
 "queueId": "8b2a1c4d-5e6f-7g8h-9i0j-k1l2m3n4o5p6",
 "wrapUpCode": null
}

The request hits the endpoint with a valid access token, but I get a 400 Bad Request back. The response body just says Invalid request body.

I’ve checked the queue ID. It exists. The user making the call has transfer permissions. I can do this manually in the UI without issues.

Is there a specific header I’m missing? Or does the PATCH body need more fields than just queueId? I’ve tried adding to with a queueId object structure but that throws a different validation error about unknown fields.