[C#] Platform Effector 2D really glitchy

I am creating a 2D platformer for a competition, and I have a problem with my semisolid platforms. I am using the internal physics engine for my character, and using the Platform Effector 2D. My problem is that when you jump through the platform from below, it has a small visual glitch you going up and down through the platform a bit before you rest on top. Here is my platform: (The SEMISOLID script is one I made before I learned about Platform Effector 2D, and it works even worse.) What is wrong with it?