I had made a 4-layout game, with 2 additional event sheets.
Just now, I made a new event sheet and saved. Somehow, after I added an action to this event sheet, it replaced all my other remaining event sheets, ruining my entire game.
I have no backup of it, as I assumed it was toggled on by default like in MMF2. I do have, however, an exectuable of my game before it messed up.