Hey @QWER9983! Welcome to the forums!
So my first question is:
I see you are using a montage. Are you also using root motion for this attack animation? Or is the actor actually staying in place?
It may be better to forego the arc if you are using root motion, and using “Set character location” on a lerp. OR creating a temporary spline for the boss to follow as it jumps. Because what you’re adding with the arc is a physics-based impulse- if physics are not enabled on the character, or they have high mass, they will be unaffected. The node you are using is for projectiles, like an arrow shot from a bow, or a mortar or cannon shot. 