I use Chrome in full-screen mode all the time, and constantly have to hover my mouse over the top to show the menu bar (sometimes I need to check which keyboard layout I'm using, or the time, or how much space I have left on my HDD, and several other statuses).
But to my madness, sometimes it simply does not work. I move the mouse over and nothing happens. I have to use gestures (4 fingers up) to display all spaces, and then the functionality returns (the menu bar slides down the next time I hover my mouse over the top of the screen).
I don't know why this happens, but this bug has been with me for years, in different macs and macOS versions.
I've gotten used to it, but now I've had enough. Does anybody know why this happen, and how to get rid of it, either by ALWAYS displaying the menu bar even in full screen mode, or to make it constantly and reliably slide down when I hover my mouse over the top of the screen?