Okay, I think I figured it out, but there is still an issue. The problem is I had the app at the default size when you first open it. However, the window size is too small for that dialog. It is actually too small for most of the dialogs, but this one, in particular, is bad because the dialog it spawns is too small to show the buttons and you cannot click on anything to get out of it.
The procedure to recreate this issue is as follows:
Open CCleaner and drag the window size down to it smallest size. This is the default size when you first install and run CCleaner.
Run a health check
Click on Privacy (you will see the button is cutting off on the Manage allowed websites)
Click the Manage allowed websites button (It is still okay at this point as there is a scrollbar to allow you to scroll this interface inside the smaller window.)
Click Add frequently chosen websites
At this point, you have a new dialog that has no way to exit because the buttons are off the screen and you can't click them to close it. Also, the main screen is greyed out as the new dialog has priority and must be closed before you can do anything else.
All this being said all I have to do is size the window larger at the beginning and when that dialog gets created, it will be big enough to show the buttons. But, the interface shouldn't be allowed to shrink down too small to show buttons, nor should that be the default size.