Character "snaps" to one-way PlatformEffector2D?

I set up a one-way platform with an EdgeCollider2D and PlatformEffector2D, but I noticed that my character "snaps" to the surface of the platform when he jumps around 3/4 of the way into it.

This is a problem because I coded a platform drop-through function that disables the edge colliders when the player presses down, but if you just tap the down button, the character only falls a little before snapping back to the surface.

It seems that there's an invisible threshold the character has to cross in order to be considered on the platform but I can't find a variable for that.