Are the properties/fields that the parameters are targeting, decalred on your custom Action Clip? If so is there a reason you want to manually add those animatable parameters instead of placing the [AnimatableParameter] attribute on top of these properties/fields? Just want to clarify the use case 🙂
With that said, there are indeed some code changes needed to be able to do this (manually adding animatable parameters that target properties/fields on the action clip itself), because there is the assumption/expectation that animatable parameters targeting the action clip are added with the said attribute instead.
Gavalakis
