itch.io

I think Mac only keeps your last 'block app' in memory for a short period of time, so open the app again and then immediately go to the settings to check it.

If that doesn't work, it could be a myriad of things, including if you have admin access to the Mac or some other issue that I'm not aware of.  

Again, if the problem persists, you can always use Steam or the Itch.io Game Launcher.  

Mac will usually allow opening of games downloaded from either of them.