Hi,
Have you checked "EveryFrame" and let the state active during the damping?
Else, I am not sure, because this damp is a built in function provided by the Unity Api itself, so maybe you should first investigate a working sample even if in c#, and use the same Animator graph and control it with this action and compare the results. That would be how I would go about it to testify it works.
Bye,
Jean