[UE5.5 GASP] Right Arm with Weapon Attached to Hand_R Moves Incorrectly During Anim Montage with Layered Blend Per Bone (Upperbody)

I’m using the Game Animation Sample and have encountered an issue where a weapon attached to hand_r moves incorrectly or causes the arm to break when playing an Anim Montage that uses Layered Blend Per Bone.

The problem does not occur in regular Animation Sequences, but when the Anim Montage is played, the hand and weapon are affected in an unintended way.

Right arm moves unnaturally, showing a broken arm animation. It seems like Layered Blend Per Bone is affecting hand_r, even though I want only the upper arm and clavicle to be influenced.

This is my arm when playing anim montage using this ABP.

Any insights or recommendations would be greatly appreciated!