Cannot authenticate with sudo su - when following the example

I followed the example: Switch to root with "su - root" exactly, except that the command is "sudo su - #user#" and when I write the password to the stream it always returns invalid password.

I checked if I had the wrong password (copy and paste works when logging in with putty).
I checked the encoding and everything says UTF8. I manually set UTF8 encoding also in the connectionInfo when connecting.
I checked the string that is send in debug mode and it seems correct.

Anyone has any suggestion why it wouldn't work? Any setting I need to change?
Or does it simple only work with and su - #user# and not sudo su - #user#?

All the commands that do not need a user switch seem to work fine

Start by reproducing the documented su - root example and compare it with sudo su - #user#, using the issue's password and UTF-8 checks as context. Done means identifying why the sudo variant rejects the password and confirming whether the example supports that command form.