My Character is Jumping at different heights with physics for no reason

My Character is jumping at different heights and I just cant figure out why?

My Character jumps at a shorter height when he is standing right beside a cube. Why is this happing, i do not have friction on it, it shouldn't work this way.

The character have the following components attached:

• Capsule Collider With Physic Material:

  *Dynamic Friction: 0; *Static Friction: 0; *Bounciness: 0; *Friction Combine: Minimum; *Bounce Combine: Minimum; *Firction Direction 2: (0, 0, 0); *Dynamic Friction 2: 0; *Static Friction 2: 0;

• Rigidbody:

  *Mass: 1; *Drag: 0; *Angular Drag: 0.05; *Use Gravity: true; *Is Kinematic: false; *Interpolation: None; *Collision Detection: Discrete; *Freeze Position: (0, 0, 1); *Freeze Rotation: (1, 1, 1);

• And a Script with the following code:

  ---

      using UnityEngine;
       using System.Collections;
       
       public class SimplePhysicsTest : MonoBehaviour {
           
           public float moveForce = 20;
           public float jumpForce = 300;
           
           [System.NonSerialized]
           public bool grounded = false;
           
           void FixedUpdate () {
               // Get Inputs
               float moveInput = Input.GetAxis("Horizontal");
               bool jumpInput = Input.GetButtonDown("Jump") || Input.GetKeyDown(KeyCode.UpArrow);
               
               
               // apply movement
               if(moveInput != 0) {
                   rigidbody.AddForce(Vector3.right*moveForce*moveInput);
               }
               
               // apply jumping
               if(jumpInput && grounded) {
                   MDebug.Print("jump force: "+jumpForce+"N @ "+MUnity.SecondsToString((int)Time.time));
                   rigidbody.AddForce(Vector3.up*jumpForce);
               }
               
               MDebug.md.debugText = "Grounded: "+grounded;
               
           }
           
           
           
           // Checking if grounded
           void OnCollisionEnter(Collision collision) {
               if(IsGroundCollision(collision)) {
                   grounded = true;
               }
           }
           void OnCollisionStay(Collision collision) {
               if(IsGroundCollision(collision)) {
                   grounded = true;
               }
           }
           void OnCollisionExit(Collision collision) {
               if(IsGroundCollision(collision)) {
                   grounded = false;
               }
           }
           bool IsGroundCollision(Collision collision) {
               Vector3 mostGroundedPoint = Vector3.zero;
               foreach(ContactPoint cp in collision.contacts) {
                   if(cp.normal.y > mostGroundedPoint.y) {
                       mostGroundedPoint = cp.normal;
                   }
               }
               return (mostGroundedPoint.y >= 0.5f);
           }
   
   }
    
  
  

  ---

There is nothing else to it other then the mesh render and unrelated stuff

The tiles are the default Cubes in unity with a material on it and they are positioned perfectly from each other ie: cube1 (0,0,0), cube2 (1,0,0), ... etc

Can anyone tell me why he is not jumping the same height?

Note: (I don't own the art in the game, I'm using it only to learn and I'm not going to publish this game)

[1]: http://mudhishcode.com/test/platformer/Web.html