Context.ContentResolver。Delete为某些联系人返回0

我有一个奇怪的问题。我正在尝试从设备中删除基于给定电话和/或电子邮件地址的联系人。我在设备中有150个联系人,所以它删除了大约100个联系人,但其余50个并没有删除。

我使用以下代码删除联系人(此方法是从循环中调用)。

public bool DeleteRecord(string phoneNumber, string email)
{
    var Id = "0";
    var isDeleted = false;
    string lookupKey = string.Empty;
    try
    {

    var uri = ContactsContract.Contacts.ContentUri;
    string[] projection = {
        InterfaceConsts.Id,
        InterfaceConsts.DisplayName,
        ContactsContract.Contacts.InterfaceConsts.LookupKey
        };
    var uri1 = Android.Net.Uri.WithAppendedPath(ContactsContract.PhoneLookup.ContentFilterUri, Android.Net.Uri.Encode(phoneNumber));

    var cursor = appContext.ContentResolver.Query(uri1, projection, null, null, null);


    if (cursor.MoveToFirst())
    {
        do
        {
            Id = cursor.GetString(cursor.GetColumnIndex(projection[0]));

            if (Id != "0")
            {
                int idx = cursor.GetColumnIndex(ContactsContract.ContactsColumns.LookupKey);
                lookupKey = cursor.GetString(idx);
            }
            break;
        } while (cursor.MoveToNext());
        cursor.Close();
    }
    isDeleted = Id != "0";
    if (isDeleted)
    {
        var u = Android.Net.Uri.WithAppendedPath(ContactsContract.Contacts.ContentLookupUri, lookupKey);
        var res = appContext.ContentResolver.Delete(u, "contact_id=" + Id, null);
        return true;
    }
}
catch (Exception ex)
{
    Android.Util.Log.Error("Error:", ex.Message + " " + ex.StackTrace);
}


return false;
}

所以不确定这里出了什么问题。对此有什么想法吗?