Thank you for the info. So, Rebex should be able to authenticate as well.
To determine what is going on, please create Verbose communication log and post it here, or send it to email@example.com for analysis.
It can be created like this:
var client = new Sftp();
client.LogWriter = new Rebex.FileLogWriter("c:/data/sftp.log", Rebex.LogLevel.Verbose);
Please create also second log with only keyboard-interactive enabled. It can be done like this:
// set SSH session parameters before calling Connect() method
client.Settings.SshParameters.AuthenticationMethods = SshAuthenticationMethod.KeyboardInteractive;