why will my jump animation only play on multi-jumps?

I have a script dedicated to the players movement, which recently I added the animation changing to, it seems to work fine bar 1 thing, when the player jumps, the jump animation plays for less than a second before reverting to whatever animation they had while on the ground, but the animation plays as expected on double / multi jump.

Here is my script, commented how I saw fit, hopefully anyone helping will be able to stick the pieces together while reading it, if anything isnt clear.

 using UnityEngine;
 using System;
 using System.Collections;
 using System.Collections.Generic;
 
 public class PlayerControlScript : MonoBehaviour {
  
  [Serializable]
  public class MoveInformation //Move information to keep the settings friendly
  {
  public float Acceleration = 1;
  public float Deceleration = 1;
  public float MaxSpeed = 10;
  }
  Vector3 previousDirection; //private Move associated variables
  bool onGround = false;
  float Speed = 0;
  
  [Serializable]
  public class JumpInformation //Jump information to keep the settings friendly
  {
  public int Limit = 2;
  public float Delay = 4;
  public float Speed = 20;
  }
  int hasJumped = 100; //private Jump associated variables
  float jumpTimer = 0;
  
  public float slopeLimit = 0.4f; //to what degree does a surface coutn as the ground
  public JumpInformation jump;
  public MoveInformation move;
  public PlayerCameraScript.ViewInformation view;
  PlayerCameraScript playerCamera; //player Camera control helper
  
  void Awake()
  {
  previousDirection = transform.eulerAngles;
  GameObject temp = Instantiate(Resources.Load("CameraObject")) as GameObject; //create an object to host the Camera control helper
  playerCamera = temp.GetComponent(typeof(PlayerCameraScript)) as PlayerCameraScript;
  playerCamera.InitiateCamera(transform);
  playerCamera.view = view;
  }
  
  void Move(Vector3 temp) //Handles movement to keep code readable
  {
  Vector3 velocity = rigidbody.velocity;
  if (onGround) //if on ground allow change in velocity
  {
  velocity.x = temp.x;
  velocity.z = temp.z;
  }
  if (jumpTimer > 0) //if jump is delayed count down the timer
  { 
  jumpTimer -= Time.deltaTime * 10; 
  }
  else if (Input.GetAxis("Jump") != 0 && hasJumped < jump.Limit) //if player can jump
  {
  hasJumped++; //add jump interval
  jumpTimer = jump.Delay; //delay next jump
  velocity.y = jump.Speed; //set the speed
  velocity.x = temp.x;
  velocity.z = temp.z;
  animation.CrossFade("jump"); //set the animation
  animation.Play(); //make sure it plays every time a jump, doublejump or multi-jump takes place.
  }
  
  rigidbody.velocity = velocity; //set velocity changes
  }
  
  void Update () 
  {
  Vector3 inputV = playerCamera.transform.forward; //get camera relative controls
  inputV.y = 0;
  Vector3 inputH = playerCamera.transform.right;
  inputH.y = 0;
  Vector3 input = (inputV.normalized * Input.GetAxis("Vertical")) + (inputH.normalized * Input.GetAxis("Horizontal"));
  inputV = transform.eulerAngles;
  inputV.y = Mathf.Atan2(input.x, input.z) * Mathf.Rad2Deg;
  transform.eulerAngles = inputV;
  
  if (input.magnitude != 0) //if controls are pressed do acceleration calculations
  {
  Speed += Math.Abs(input.magnitude) * move.Acceleration;
  if (Speed > move.MaxSpeed) Speed = move.MaxSpeed;
  previousDirection = transform.eulerAngles;
  }
  else //else do deceleration calculations
  {
  Speed -= move.Deceleration;
  if (Speed < 0) Speed = 0;
  transform.eulerAngles = previousDirection;
  }
  
  Move (input * Speed); //execute Move (explained above)
  
  if (Input.GetAxis("Action") != 0) //not in use currently, if action is pressed, print interacted object
  {
  RaycastHit rayCastInfo;
  if (Physics.Raycast(transform.position + new Vector3(0,1,0), input, out rayCastInfo, 5))
  print(rayCastInfo.collider.gameObject.name + " at " + rayCastInfo.point);
  }
  animation["walk"].speed = Speed / 4; //set walk animation speed
  if (onGround) //if on the ground check and change animation (idle and walking)
  {
  if (Speed > 0 && animation.clip.name != "walk")
  {
  animation.CrossFade("walk");
  }
  else if (animation.clip.name != "idle")
  {
  animation.CrossFade("idle");
  }
  }
  }
  
  void OnCollisionStay(Collision collision) 
  {
  onGround = false;
  foreach(ContactPoint point in collision.contacts)
  {
  if (Vector3.Dot(new Vector3(0,1,0), point.normal) > 1 - slopeLimit) //if colliding with a surface within the ground limit, set onGround to true
  {
  onGround = true;
  hasJumped = 0;
  }
  }
     }
  
  void OnCollisionExit(Collision collision) //on collision exit onGround = false, if player did not jump off surface, pretend they did.
  {
  onGround = false;
  if (hasJumped == 0) hasJumped++;
     }}

I'm unsure whats going on, nothing special runs when there is a multi-jump, its exactly the same as a normal jump except the players expected to already be airborne.

Any and all help is greatly appreciated, Thanks in advanced, Bombshell