I finally got Scaler 2 to work! Unbelievable!
I read this thread
And I went to the NVIDIA Control Panel and I set Cubase to run on the integrated graphics card. It works now! So it appears that it is a graphics problem. I really hope that Scaler 2 is patched in a future version so that this workaround is not required and so that I will not have to worry about Scaler 2 being compatible with the graphics card, when I move to a new computer.
Thanks again to the Scaler 2 team for trying to help over the last weeks!