SearchCondition.SentSince seems not working

[bigbadabam]

I used SearchCondition.SentSince to filter messages by date, but in the following example search method returns empty uids collection:

 static void Main(string[] args)
        {
            string hostname = "imap.yandex.ru", username = "[email protected]", password = "mypass";
            using (ImapClient client = new ImapClient(hostname, 993, username, password, AuthMethod.Login, true))
            {
                Console.WriteLine(">> Connected");
                IEnumerable<uint> uids = client.Search(SearchCondition.SentSince(new DateTime(2018, 01, 01)));                    
                Console.WriteLine(">> Mail list received");
                IEnumerable<MailMessage> messages = client.GetMessages(uids);
                Console.WriteLine(">> Messages received");
                //string[] keys = { "Date", "From", "Return-Path" };
                string[] keys = { "Date"};
                foreach (var message in messages)
                {
                    foreach (string s in keys) 
                    {
                        Console.WriteLine("    {0}: {1}", s, message.Headers[s]);
                    }
                    Console.WriteLine();
                }
            }
            Console.ReadLine();
        }

When I used SearchCondition.All() I have following output:

Date: Thu, 05 Feb 2015 20:30:02 +0300
Date: Sun, 11 Dec 2016 14:58:23 +0400
Date: Sun, 11 Dec 2016 20:38:14 +0400
Date: Thu, 27 Jul 2017 17:41:57 +0400
Date: Tue, 03 Oct 2017 12:36:48 +0300
Date: Tue, 03 Oct 2017 15:42:34 +0300
Date: Tue, 03 Oct 2017 22:19:05 +0300
Date: Wed, 4 Oct 2017 16:30:46 +0400
Date: Sun, 08 Apr 2018 10:16:16 +0300
Date: Fri, 13 Apr 2018 09:56:55 +0000
Date: Tue, 30 Oct 2018 14:46:35 +0400
Date: Mon, 14 Jan 2019 14:09:47 +0300
Date: Fri, 22 Mar 2019 15:09:52 +0300
Date: Tue, 26 Mar 2019 11:30:13 +0300
Date: Thu, 28 Mar 2019 13:30:44 +0300
Date: Tue,  2 Apr 2019 17:20:28 +0300
Date: Tue,  9 Apr 2019 17:00:36 +0300
Date: Thu, 18 Apr 2019 18:10:13 +0300
Date: Fri, 19 Apr 2019 00:19:25 +0300
Date: Fri, 19 Apr 2019 07:45:51 +0000
Date: Fri, 19 Apr 2019 15:01:21 +0300
Date: Tue, 23 Apr 2019 15:31:19 +0300
Date: Tue, 30 Apr 2019 12:30:04 +0300

So what's wrong?

[rvalitov]

I'm using another tool and in my case the "SENTSINCE" and "SENTBEFORE" are ignored by Yandex. "SINCE" and "BEFORE" do work.