Undo History question

Hello there, wonder if anyone has noticed this. The MPC Bible says that you can go to the Menu and tap on the undo history icon (it looks like a clock on the top row) and then you can simply tap on the point where you'd like to return your project to and the MPC undoes everything to that point. But when I go to the undo history screen, the entries there not tappable. They are just there like for only display purpose. Am I missing something?