VK API. getLongPollServer and getLongPollHistory. Why doesn't it catch all events?

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VK API. getLongPollServer and getLongPollHistory. Why doesn't it catch all events? It does not work every time, I tried to display new_pts, sometimes some values ​​​​are missing. It also doesn't work in conversations. Code below. What's wrong?

static void Main(string[] args)
        {
            connectToLongPool();
            while (true)
            {
                scanMessages();
                Thread.Sleep(500);
        }
public static string ts;
        public static string pts;
        public static string new_pts = "1";

private static void connectToLongPool()
        {
            HttpWebRequest pollReq = (HttpWebRequest)WebRequest.Create("https://api.vk.com/method/messages.getLongPollServer?access_token=токен_от_группы&need_pts=" + new_pts + "&v=5.92");
            pollReq.Method = "GET";
            pollReq.Accept = "application/json";
            HttpWebResponse pollResp = (HttpWebResponse)pollReq.GetResponse();
            StreamReader reader = new StreamReader(pollResp.GetResponseStream());
            StringBuilder builder = new StringBuilder();
            string pollData = builder.Append(reader.ReadToEnd()).ToString();
            JObject poolConnectJson = JObject.Parse(pollData);
            ts = poolConnectJson["response"]["ts"].ToString();
            pts = poolConnectJson["response"]["pts"].ToString();
        }

private static void scanMessages()
        {
            HttpWebRequest poolMessages = (HttpWebRequest)WebRequest.Create("https://api.vk.com/method/messages.getLongPollHistory?group_id=190776459&ts=" + ts + "&access_token=" + "токен_группы&v=5.92" + "&pts=" + pts + "&lp_version=3&msgs_limit=10000&events_limit=10000");
            poolMessages.Method = "GET";
            poolMessages.Accept = "application/json";
            HttpWebResponse poolResponse = (HttpWebResponse)poolMessages.GetResponse();
            StreamReader reader = new StreamReader(poolResponse.GetResponseStream());
            StringBuilder builder = new StringBuilder();
            string textResp = builder.Append(reader.ReadToEnd()).ToString();
            JObject poolConnectJson = JObject.Parse(textResp);
            Console.WriteLine(textResp);
            //MsgPrint(poolConnectJson);
            new_pts = poolConnectJson["response"]["new_pts"].ToString();
            Console.WriteLine(new_pts);
        }