DeleteFeaturesAsync没有真正删除要素

版本为arcgis runtime 100.0, layerUrl为feature layer url，我的代码如下：执行完成了，也没有提示任何错误，但是并没有真正删除数据。
public async Task DeleteFeatures(string layerUrl, QueryParameters queryParameters)
{
var featTable = await GetFeatureTable(layerUrl);
if (null == featTable)
throw new Exception("if (null == featTable)");
var items =await QueryFeatures(layerUrl, queryParameters);
if (null == items || items.Count <= 0)
return;
await featTable.DeleteFeaturesAsync(items);
}