Hi,
I am stepping in because editing official Actions is a very bad idea, everytime you'll update PlayMaker, your changes will be lost and you'll have a buggy project...
AddForce must only be set in FixedUpdate.
If you have a case where you think it has to be done on lateupdate, I would be interested to hear more about it.
If you MUST edit an official action, make sure you duplicate it, rename it like "AddForceLateUpdate" or something, and use that one, and then you'll be totally safe.
Bye,
Jean