Have you correctly set the animation center for each of your characters animations? If you haven't set the animation center for each of the characters animations & you change to one of said animations then it will likely look like your character disappears/moves off of the screen because of the offset caused by the incorrect animation center. The animation center you specify for each characters animations is used to position the character on the scene.
Have you accidentally created any stray nodes in the way borders section? The way border requires a full circuit otherwise issues can occur.