I want to move the arm with the mouse input.
The value of the rotator that the string prints in the log is correct, as you can see this rotator is the mouse position normalized. The variable of the rotator comes from the character blueprint since I also use this to make the aim dead zone. And yes, the transform modify bone has been set to modify the upperarm_r and to not ignore the pin of rotation.
But the arm does not twist accordingly.
AnimGraph:
EventGraph of Character BP:
I have also tried Two Bone IK and FABRIK with same results. It just plays the normal running animation but it does not allow me to controll the arm.