This is just an issue only you as an author deals with. When you change a characters features or make a character become another character when using the app, that character will always stay that way. So when you make your character become the plus character and then try to replay your story, the generic character stays as the plus character and that’s why it glitches because you’re trying to change them into a generic body.
But only you see this issue when you replay or retest your story in the app. This doesn’t affect your story at all. Your readers won’t experience this glitch because they only play through your story just once.