Fighting bug

Ive only just started playing this on my iPad Mini 2, but Im having a problem. When Im trying to fight the slider wont register so Im constantly stuck in defence position. Sometimes itll glitch and jump about so Im either attacking with a lot of strength or very little - Im never in control.

Im giving it three stars right now because so far the game looks beautiful and Im excited to progress, Im just unable to. I hope youll be able to fix this!

Petmonster2104 about Sorcery!, v1.5.1