I have never done those tutorials but I know that the sprite render can be a pain sometimes. It may be that your animation itself that is causing the invisible issue. Also Make Sure that the camera is Orthoscopic and that it is not under the ground.
I wish we could @ mention people. Vitinho could perhaps help with this one.
EDIT: I have never used Unity before, but I do see a "scale" option in the right bar. Is that only for things placed in the level or could you use that on the player sprite?