Hide Menubar does not work on Windows

[Microtribute]

OS
Windows

Gmail Desktop Version
v3.0.0-alpha.34

Describe the bug
Checking that menu item is originally supposed to hide the menu bar and make the window title bar use the system style. Restarting the application or even restarting the whole system didn't bring up the change. I remember it used to work before.

Steps to reproduce the behavior
Please check the attached screenshot.

Expected behavior
Hide the menu bar (as well as the hamburger menu icon). Click the Alt key to bring back the menu bar.

Media