PATCH /conversations/voice/{conversationId} transfer to queue failing with 400

Trying to transfer a call to a queue via PATCH /api/v2/conversations/voice/{id} but hitting a 400.

const body = {
 to: { id: 'queue-uuid', type: 'queue' }
};

Docs say this works, but the error just says ‘Bad Request’ with no detail. Is the to payload structure wrong? Or do I need specific scopes like conversation:write?