ssh_dbg:start doesn't call custom function

Hello.

I'm working with an ssh/sftp server daemon being called from Elixir.

While troubleshooting a particular SFTP client program being unable to connect with our SFTP server, I discovered the ssh_dbg module.  It looks like this module can accept a function for customizing the output, but when calling it, it seems to be using its internal implementation.

I know this module is marked as experimental, but does anyone see anything immediately wrong?

        :ssh_dbg.start(fn format, args ->
          IO.inspect format
          IO.inspect args

          :ok
        end)
        
        :ssh_dbg.on(:messages)