I've having some trouble animating my donut. When it reaches the surface there's a gap between the objects, and sometimes the object jitters and bounces when it reaches the surface and I don't understand why that happens.
It looks as though you already have taken care of making sure that Collision Type is set to "Mesh" and that the Margin is set nice and low. I can only suggest that you check all your participating objects for these settings and perhaps lowering the margin setting even more. It may help to apply scale, as suggested by the gentleman who answered this similar question.