does the layer additive blending in the animator work?

I am trying to use an animator layer to make my character bend his back forwards and backwards so he will look in the vertical direction of the camera. I made a layer with an avatar mask that takes only the back where i put a blendtree with the maximum and minimum back bending. I tought the best was to use additive blending in the layer settings, but it doesn’t seem to work, while override works, but it cripples the other animations. Does anybody have any suggestion to help or maybe I am using the wrong solution? Thanks in advance.

Of course it works. Just remember how the weighting system works, from the highest layer down to base. You may find that your additive layer is being overridden by a layer above it.

You can either use an Avatar Mask to specify which bones to use and which to leave out or go back and deselect the bones you dont want to include when KeyFraming your rig.

Sometimes it would seem that animations can interfere with each other and extra rotations will either not occur or bug-out in some way. The answer in this case is to make use of LateUpdate() for certain operations.