PATCH /api/v2/conversations/voice not updating queue target

Docs state: “To transfer a call, use the PATCH method on the conversation endpoint with a transfer action.” I’m sending a valid access token and the correct conversation ID. The request returns HTTP 200 OK, but the call stays in the original queue.

PATCH /api/v2/conversations/voice/{id}
{
 "action": "transfer",
 "target": { "id": "new-queue-id", "type": "queue" }
}

Why isn’t the transfer executing? The JSON structure matches the spec.