@Kurt258 I somehow just managed to fix this... And now I'm even more confused...
I closed ASUS GPU Tweak 3... Thats it... No antivirus adjustments, no uninstalling and re-installing, no tweaking files... Just closing that program...
Not sure why, but you're not the only one to complain about it. A lot of user did when the Opera One UI came out. I've complained about it too. There are also a lot of other spots in the UI for clicking at the edge of the window doesn't trigger a click on the target element.