After updating to version 13.1 on macOS 12.4, I discovered that the keyboard shortcut for typesetting a fraction (Insert > Typesetting > Fraction) has changed. In previous versions, the shortcut was Ctrl + /, but now is Ctrl + ´. The old shortcut doesn't do anything in 13.1. I tried following this answer to change the keyboard shortcut. To my surprise, line 65 of the file KeyEventTranslations.tr reads Item[KeyEvent["/", Modifiers -> {Control}], "Fraction"], which is just the old shortcut. So...
