Because Show Original is a “state” – which means that you enter Show Original and then have to exit Show Original. You have to release the M key or release the button. So, it’s possible for the app to “miss” the exit and then be confused. So, my guess is that at some point, the app got confused and was not properly handling the Show Original state. Quit / reopen will fix that because it clears out the incorrect state in the app. Sorry.