Facebook受众人数不可用（approximate_count = -1）

Question

当我尝试检索Facebook sdk / graph api自定义受众当前大小API时，返回"approximate_count": -1.

https://graph.facebook.com/v3.2/{custom_audience_id}?access_token={access_token}&fields=approximate_count,delivery_status,operation_status"]

结果=

{
    {
    "approximate_count": -1,
    "delivery_status": {
        "code": 200,
        "description": "This audience is ready for use."
    },
    "operation_status": {
        "code": 200,
        "description": "Normal"
    },
    "id": "{custom_audience_id}"
}

在这里，我希望获得近似值作为实际值。但是我得到-1。任何帮助???