Flash settings won't go away, no matter how much you click "Allow" or "Deny"

This is Flash Player's anti-clickjacking logic being overzealous.  When we show permission dialogs, we need to know that they're not obscured by other content on the page.  Because we're a plug-in, and not the host browser, this problem is ugly. 

In essence, what we do is sample the pixels where the dialog is displayed and we check to see that they match our expectations about what *should* be there.  This is imperfect (and fixing it tends to be a game of whack-a-mole -- we make a change for one configuration, and it breaks three others), and it's particularly problematic if the dialog pops up over the top of anything moving, like video.

The best way to deal with it is to just avoid having the dialog pop up in the first place.  If you go to Settings > Flash Player > Storage, and choose "Allow Sites to Store Information On This Computer", you won't run into the dialog.  Blocking local storage with Flash Player doesn't really buy you anything in terms of privacy in 2017, and you're far, far better off using your browser's private browsing mode (in combination with a trustworthy VPN service) if you're worried about your online footprint.  Efforts by browsers to deprecate Flash Player mean that advertisers and other entities engaged in tracking your online habits have largely shifted away to much more powerful capabilities offered directly through HTML5 and JavaScript, and server-side tracking by your ISP (thank your congressional representative for that).  Good times.

Hope that helps!