Undo mode does not work

Hi @Paul_Gringo, 

I'm sorry to see you can't use Undo. Just to confirm, you have made some actions to Undo. If nothing has been done, it will be grayed out.  If you navigate to Windows > History, you should be able to see all your most recent actions.  If you need to use a bunch of Undos, click the hamburger menu and choose settings, and you can change the number of Undos.

I hope that helps.  If not, we'll need a bit more information.  Please see: How do I report a Problem?