Had the same issue: a blank Activation screen.
Using a new Surface Pro 8 with Windows 11.
What worked for me was changing the scaling to 125% and the resolution to 1920 x 1080.
Other combinations would show some of the dialog box contents but not all, or would not allow input even when the activation code text entry was visible - someone suggested moving the mouse down just in case the graphic and actual input area were misaligned - this did not work.
Other combinations of scaling and resolution would show part or all of the dialog box, but only the combo above worked for me. I am sure that Your Mileage May Vary.
What Intuit / TurboTax should do is throw together a quick command line tool to allow running an activation from the command prompt. Since the GUI is messed up anyway and requires this jiggery-pokery to get it working, using such a tool wold be a quick and easy work-around for users and a quick solution for both them and the tech support people.
Hope this helps.
