DS 4.16.0.3 dForce collision irregular pokethrough error

AprilYSH

Heyas, when I run cloth simulation (on a poly hair model) sometimes the hair ends will pokethrough through g8f chest. So I clear sim data, change collision mesh res to "Viewport" and run the sim again, this time it works without pokethrough. Then I change collision mesh res back to "Base" (the default) and again it works without pokethrough.  So I'm not sure why sometimes it pokes through and just toggling between the collision mesh res resets something and it works again?  I changed nothing else but collision mesh res = default base, to viewport, and back to default base. Not even camera angle to be sure the viewport setting is not affected by it. Has anyone else had this happen?   Thanks.