JuanMorello I'm starting to think the problem is the animation I did before starting the simulations
Do you have a run up that goes from default pose into your animation start pose?
You may also want to set keyframes on gravity. 0 -> -9.8 over 10 frames or so.
I see you have a keyframe on skin_innerMaterial.pressure. This keyframe won't have any affect on the simulation. The value at zSolver.start will be used and any changing values through out the sim will be ignored.
That said, I see you have keyframes on the corresponding envelope values, that's good. That's the correct way to make those parameters vary over time (at the time of writing 🙂 )