As we can see on this playground we’re adding speed to a 0 mass mesh, the Mesh itself don’t move at all, but the speed does move the cylinder above it, this isn’t a bug?
Shouldn’t the ground mesh move with its PhysicsImpostor or the cylinder not move as the mesh below?
Why does the mesh don’t move, but the linearSpeed on the ground mesh affects the cylinder above it?
It all depends on what you want to do. I would base my physics on edge cases like this. Maybe a newer version will change that behavior. I would stick with well defined behavior.