Are you referring to the activation screen at the end of installation? This answer assumes that is what you are experiencing.
Are you using Windows? If so, a blank, partially-blank, or missing activation screen may be related to either a screen resolution or scaling problem in your Windows settings.
In Windows 10 to get to the scaling or resolution settings click the Windows start button in lower left corner, then choose Settings (gear icon), then System, then Display. Or for a shortcut, you may be able to simply right-click on an empty area of the main Windows desktop monitor screen (not the TurboTax program screen) and in the popup menu choose "Display settings".
NOTE: After you change the scaling or resolution setting as discussed below, you may need to close and relaunch TurboTax for the change to take place in that activation window.
First try the scaling setting. In your Windows Settings do you have scale set to a higher value than the normal 100%? If so, change it back to 100%. Once the license code is entered and activated, you can later change your scaling setting back like it was.
If lowering the scaling to 100% didn't help, then it may be screen resolution. Try a lower screen resolution such as 800x600. If that doesn't work, then try 1024x768. If still not working, then gradually increase the screen resolution to the next level. Once you get the license activated, you can revert your resolution setting back like it was.
I'm kinda perplexed by that new FAQ. I'm not sure that's the most common cause. While it may be a cause with a really old video card, I would blame it on TurboTax developers/programming before I'd blame hardware. I bet most of these folks are not having such problems with other software activations/purchases.
Many of these folks who are having activation screen problems are using new laptops with new video cards/drivers, and the newer laptops have high-resolution screens, which TurboTax appears to not be well-prepared for.
Most folks can resolve it with the scaling/resolution suggestions I mentioned above.