So the way it works is when you have a enemy targeted, it will cast your heals on you if you don’t have your mouse over someone or their frame. So it can be a little tricky to use at times, yet works well in my opinion over other macro’s. Now of course if you have a player targeted, or a friendly entity then it will just solely cast on them, until you click an enemy or someone else. Which brings me why to I also like it given I can sort of hard set someone to heal when their taking a lot of damage, then sue the mouse over component to heal others as needed.
Are you also using heal bot? Though I can’t remember if it casts on frames for MO.