Sometimes the tops of maximised windows stops rendering in one of my monitors – I just get a blank space instead, hiding menu, title bar controls etc.
Use [⊞ Win] + [Ctrl] + [⇧ Shift] + [B] to refresh the display in case of screen lockup.
(From https://answers.microsoft.com/en-us/windows/forum/all/top-of-the-window-gets-cut-off/1fbd8709-dc67-4127-a528-c259dba6aae3).