小商店库存无法更新，接口不生效，不报错

$url_kc = "https://api.weixin.qq.com/product/stock/update?access_token=".$access_token;   //更新库存
$arr_kc=array("product_id"=> 86475679,"sku_id"=>"316621211","type"=>2,"stock_num"=> 100);  //增加100的库存
$data_kc = json_encode($arr_kc,JSON_UNESCAPED_UNICODE);
$res_kc=http_request($url_kc, $data_kc);
print_r($res_kc);
POST请求包体
{"product_id":86475679,"sku_id":"316621211","type":2,"stock_num":100}
返回以下数据，但是库存没有更新成功
{"errcode":0,"data":{"update_time":"2022-04-27 17:12:57"}}