HitReaction Setup

Well make sure your Collision Setup is correct. Are they both set to Block? Are you sure you reach the Add Impulse node and the Bone is not empty? (Print String the Bone Name at the end) also the Blend weight is a value between 0-1.

All I can Tell you is that its working fine at my Side like expected. Looks like its just your Projectile that makes trouble not hitting anything.