Question OnCollisionEnter2D triggered is not equal every time

Hello, I am a begginer with Unity, and for that exuse my question (and my english ), but cannot understand why collision detection is not triggered every time on equal positions of both objects. In this case (on screenshots) ball is static 2d rigidbody and spring is 2d colider with dynamic cnanged offset. Sometime collision is triggered on time, but sometime very late. I supose the reason is update rate, but I bellieve have solvation.