Sprite collision area stabs other sprites

Im new to ue4, but my problem is that i have a sprite (a half circle) and moves a lot, then another actor (balls) start falling but sometimes the balls with the fast movement of the half circle get stuck in the collision area, i have tried with the overlap event but since the sprite source is a square, it looks like it overlaps too early. All of this is kind of paper 2D, and i saw the 2D physics is experimental so im doing something wrong? or i should replace my 2D actors with meshes?

it looks like this