a few weeks ago this started to happen: sometimes, in a maximized Chrome window, the tabs would not reach the top end of the screen. If that happens, it's possible to click 'over' a tab while trying to click on it. Nothing happens, the tab isn't activated. (I hope you know what I mean.) If that happens I use Win+Left to make the window smaller and then Win+Up to maximize it again. That fixes it.
Did anyone else notice this? I've tried Google but didn't find anything. The issue is still there after the latest Chrome update.