@lorna
USING MACOS VENTURA M1 - 16".
IT DOES KEEP HAPPENING TO ME;
IT'S LIKE F.LUX DOESN'T KNOW WHAT'S F.S. OR NOT.
AND APPS DO NOT APPEAR IN THE LIST OF RECOGNIZED.
ON WINDOWS YOUTUBE GOING FULLSCREEN IS CONSIDERED AN APP THAT'S FULLSCREEN, NOT "CHROME". I'D LIKE THAT.
@Lorita f.lux has a feature to disable for certain apps. So while you're running Chrome check the f.lux "Disable" menu to see if that's what is going on.
@anewoman on some Macs, the f.lux icon will be hidden when using an app with too large a menu. If you switch to a different app, it should appear again.
It could also just be that f.lux is not running, so find the icon in Finder and run it again to be sure.
Had this same problem. Solved by moving the application to my Applications folder and running it from there. I was running it from my Downloads folder.