Yes that is a known issue, which I'm not too sure how to solve. I believe the wrapper multiplies the force based on acceleration in order to compensate.
Quote: "
Known issues:
* The NewtonRayCast doesn't seem to work reliably on Capsule primitives in the demo.
You have to be close to the capsule or at just the right angle for it to hit
I have yet to find a fix for this, it looks to be in Newton itself.
If you need this functionality then it is recommended to use Convex Hulls for your capsules
* A large angular velocity will cause RagDoll joints to spread and the model spin uncontrollably
It has always been this way and I have yet to find a fix for this, it is probably within the Wrapper.
"

A 3D marble platformer using Newton physics.