SSH Session directly closes after login

I greet you, my subjects, since the last update in 12.21, the SSH-Connection doesn't work anymore for us. We configured the ctrlX CORE as well as we know. We activated SSH and under Groups -> sshuser we activated the users we need, too. We gave the user all permissons are needed, also there we activate the checkbox sshuser and so on. But if we wanna connect via SSH to the ctrlX CORE (we use Putty and/or WinSCP) the commandline opens and asks for the credentials. We type in the user, pressing enter, than it assk for the password and after typing it in and pressing enter, the window closes without any error. Maybe there are some certificates or keys are needed, we dont know allready. What changed after the relase 12.21? Before the release, it worked well for us. Wish you all a nice weekend and with kind regards, YourHighness