Layered Blend Per Bone not working as expected

I want to have some anim montages play only on the left or right arms, however at the moment only the ‘upper body’ slot is working properly, the ‘Right Arm’ and ‘Left Arm’ slots are not working. I double checked the bone names are right in the branch filters section. The anim montages are assigned their slots as well, anyone have an idea what I’m doing wrong?