C# SSH.NET ListDirectory Not Listing Files

I'm using SSH.NET library https://github.com/sshnet/SSH.NET for communication with FTP directory using FTP over SSH.

I could successfully establish connection with Username and Private Key, but the problem is that when I'm calling "ListDirectory" for root it lists only folders but not files.

using (var Client = new SftpClient(ConnectionInfo))
{                                
    Client.Connect();
    var Files = Client.ListDirectory("");
    Client.Disconnect();
}

When I'm looking at FTP folder with FileZilla (where I also use SFTP connection) this is what I see.

When I'm executing

var Files = Client.ListDirectory("");

"Files" contains only three items: "incoming", "outgoing", "test". TestFile.txt is missing

Any idea what can possible be a reason?