2FA with Authy using WinSCP

Hello, I am using 2FA with Authy for my SSH server and it works fine but when I try to connect to the SFTP it shows an error the package received is too long! What can I do?

Hard to tell without a full log file.

Anyway, if your server issues the additional authentication prompt as part of a session (instead of properly using an SSH keyboard interactive authentication), it breaks SFTP protocol. I assume you are not able to connect with any SSH client, right?