Character Controller sticky head.... Help!?

Hello everyone,

So I have my character (capsule atm) with a character controller and a player script which has all the movement including running and jumping.

The issue i'm having is when there is an object with a collider above my player. If I jump up into the object my players head gets stuck onto this object for about 0.5/1 seconds and then falls. Whilst hes stuck i can move for a split second. If i jump at the edge of the object it will hit his head and move outwards and up and then fall.

I was wondering if anyone knew how to fix this. I've looked around but cant find anything.

Here is my script;

 private CharacterController _playerController;

 [SerializeField] private float _walkSpeed = 3.5F;
 [SerializeField] private float _sprintSpeed = 5.25F;
 [SerializeField] private float _walkBackSpeed = 2.5F;
 [SerializeField] private float _jumpSpeed = 6.5F;
 [SerializeField] private float _gravity = 20f;

 [SerializeField] private bool _sprintToggle = false;

 private Vector3 moveDirection = Vector3.zero;

 void Start()
 {
     _playerController = GetComponent<CharacterController>();

 }

 void Update()
 {
     PlayerMovement();


 }

 private void PlayerMovement()
 {
     if (_playerController.isGrounded)
     {
         /*===============================================================================================
           MOVEMENT LOGIC
         ===============================================================================================*/
         float horizontalInput = hInput.GetAxis("Horizontal");
         float verticalInput = hInput.GetAxis("Vertical");

         var speed = _walkSpeed;


         moveDirection = new Vector3(horizontalInput, 0, verticalInput);


         /*===============================================================================================
           SPEED LOGIC
         ===============================================================================================*/

         // TODO: create sprint toggle button on menu and if activated, allow speed toggle only.
         if (_sprintToggle)
         {

         }

         if (hInput.GetButton("Run") && verticalInput > 0)
         {
             speed = _sprintSpeed;
         }
         else
         {
             speed = _walkSpeed;
         }


         if (verticalInput < 0)
         {
             speed = _walkBackSpeed;
         }
         
         moveDirection *= speed;
         moveDirection = transform.TransformDirection(moveDirection);

         /*===============================================================================================
           JUMP LOGIC
         ===============================================================================================*/

         if (hInput.GetButton("Jump"))
         {
             moveDirection.y = _jumpSpeed;
         }

     }


     moveDirection.y -= _gravity * Time.deltaTime;
     _playerController.Move(moveDirection * Time.deltaTime);
 }