android export-strange behavior

Hello people.

I made a jigsaw puzzle game, that works ok in editor (and in unity remote). I tested many different resolutions, I also put the mobile simulator asset and test it in different phones (small and big) BUT... when I export it for android it has a very strange behaviour.

The pieces go and stuck in completely random places, and with completely random (as I think) order!

Here is a video I made to show it: https://youtu.be/mm-p8R_Xxus

And below is my code.

Any help would be appreciated.

 using UnityEngine;
 public class PuzzleNekNEW : MonoBehaviour
 {
     private int order = 0;
     private short i;
     private int pieceName;
     private float dist;
     private bool dragging = false;
     private bool check = false;
     private Vector3 offset;
     private Transform toDrag;
     private GameObject[] piecesObjectHierarchy = new GameObject[24];
     private Vector3[] startPositions = new Vector3[24];
     private Vector3[] startLocalPositions = new Vector3[24];
     [SerializeField] private AudioSource audioData;
     [SerializeField] private int[] check24 = new int[24];   //24 ints set to 0. When I place correctly a piece,, its position in this table is set to 1
 
     private void Start()
     {
         //take pieces from hierarchy in an array of objects
         piecesObjectHierarchy = GameObject.FindGameObjectsWithTag("pieces");
 
         //record for each object the initial local position in an Vector 3 array
         for (i = 0; i < 24; i++)
         {
             //startPositions[i] = piecesObjectHierarchy[i].transform.position;
             startLocalPositions[i] = piecesObjectHierarchy[i].transform.localPosition;
         }
 
         //distribute the pieces randomly
         for (i = 0; i < 24; i++)
         {
             piecesObjectHierarchy[i].transform.position = new Vector3(Random.Range(-1.9f, 2.6f), Random.Range(4.0f, -4.5f), 0);
         }
 
         //fill the check table with zeros (0)
         for (int j = 0; j < 24; j++) check24[j] = 0;
     }
 
     private void Update()
     {
         Vector3 v3;
 
         //if you touch with more than one fingers you cannot move the piece!
         if (Input.touchCount != 1)
         {
             dragging = false;
             return;
         }
 
         Touch touch = Input.touches[0];
         Vector3 poz = touch.position;
 
         //JUST TOUCH
         if (touch.phase == TouchPhase.Began)
         {
             Ray ray = Camera.main.ScreenPointToRay(poz);
             RaycastHit hit;
             if (Physics.Raycast(ray, out hit))
                 if (hit.collider.tag == "pieces")
                 {
                     toDrag = hit.transform;
                     print(toDrag);
                     dist = hit.transform.position.z - Camera.main.transform.position.z;
                     v3 = new Vector3(poz.x, poz.y, dist);
                     v3 = Camera.main.ScreenToWorldPoint(v3);
                     offset = toDrag.position - v3;
                     dragging = true;
                     order++;
                     
                     //send the object you touched on the top
                     toDrag.GetComponent<UnityEngine.Rendering.SortingGroup>().sortingOrder = order;
                 }
         }
 
         //MOVING TOUCH
         if (dragging && touch.phase == TouchPhase.Moved)
         {
             v3 = new Vector3(Input.mousePosition.x, Input.mousePosition.y, dist);
             v3 = Camera.main.ScreenToWorldPoint(v3);
             toDrag.position = v3 + offset;
             pieceName = int.Parse(toDrag.name);
 
             //print("v3 " + v3 + "     toDrag.localPosition " + toDrag.localPosition + "startlocalPositions[0] " + startLocalPositions[0]);
 
             //if I move a piece, its position is 0 in the check table
             check24[pieceName] = 0;
 
             //if I am close to the initial position!!! (I use Vector2 to just check x and y)
             if (Vector2.Distance(toDrag.localPosition, startLocalPositions[pieceName]) < 50f)
             {
                 print(pieceName + " IS IN!!!  " + "startLocalPositions[pieceName] " + startLocalPositions[pieceName] + "     toDrag.localPosition " + toDrag.localPosition);
                 
                 //stop moving this piece
                 dragging = false;
 
                 //it was very close, Give it the exact initial position
                 toDrag.localPosition = startLocalPositions[pieceName];
 
                 //put an 1 in the check table
                 check24[pieceName] = 1;
 
                 //send it back
                 toDrag.GetComponent<UnityEngine.Rendering.SortingGroup>().sortingOrder = 0;
             }
         }
 
         //if I leave my finger
         if (dragging && (touch.phase == TouchPhase.Ended || touch.phase == TouchPhase.Canceled))
         {
             dragging = false;
         }
 
         //CHECK if the puzzle is completed
         check = true;
         for (int j = 0; j < 24; j++)
         {
             if (check24[j] == 0) check = false;
         }
 
         if (check == true)
         {
             dragging = false;
             print("YOU DID IT!!!");
         }
     }
 }