Well if you're just wondering why, in general, particles don't always have a visible frame of contact...that's fully expected for any physics simulation.
See the attached image. The 3 steps in the second half of the panel represent calculations that happen in a single time step. Dropping the time step or time scale will reduce the effect, but not eliminate it.
See the attached image. The 3 steps in the second half of the panel represent calculations that happen in a single time step. Dropping the time step or time scale will reduce the effect, but not eliminate it.