If you're topping it with the ball teed up rather than from a ground shot, one would have to suspect , that it might be ball position. It just might be too far forward. Consequently, and since you're trying to hit up, you could be hitting it a bit late and therefore you're catching the top of the ball.

Another possible problem with topping could be that, with any ball teed up, if you're aiming too far right, you'll find you pull out of the shot a little quicker,  try to swing up,  and if you're caught  centered in the stance or with reverse weight shifting, it will have you coming out of the shot  a little too fast and you'll be topping it.

These could be two big issues. A third possible cause could be turning too a little too  much in the backswing, therefore swinging  too long, so you would have to turn harder to get the club back out in front of you. That sends the club coming outside to in. Pulling left could cause reverse weight shift and have you coming over the ball and therefore topping it.

On the other hand, if you had the ball a little too far back, you'd actually have to pull out of the shot to try and hit it because the ball's too far back and you're pounding down on it, but you're trying to come up, so you get pulled out of the shot.

It is possible you have a ball position issue here and, I think there is a high probability of over turning and over swinging, causing you to have to pull out of the shot. Plus, you could be pulling across the ball, causing reverse weight shift, making you pull out of the shot in a way that adversely affects the result.