Scratch card type code behaving abnormal now ( worked in previous version)

(Update: Found it working fine on android phone. But shows problem on pc/mac )
Simple scratch card type code. Makes use of masked layer.
That reveals the movieclip beneath when lines are drawn over the mask movieclip.
This worked without issues in previous versions. But now it does not work properly now

The problem now is that it reveals and covers up back.
With Mask:

Without mask:
package myapp;
import flash.Lib;
import openfl.Assets;
import flash.text.*;
import openfl.Assets;
import openfl.display.*;
import openfl.geom.Point;
 import openfl.utils.Function;

class Main extends Sprite 
public var appContainer_Mc: MovieClip;
public var mc: MovieClip;
 public function new() {
 addEventListener(Event.ADDED_TO_STAGE, addedToStage);
 function addedToStage(e:Event):Void 
	 removeEventListener(Event.ADDED_TO_STAGE, addedToStage);
private function loadMain(): Void
 	  appContainer_Mc =Assets.getMovieClip("library:FishObject");
	   var fishWithCut_Mc:MovieClip = cast(appContainer_Mc.getChildByName("fishWithCut_Mc"),MovieClip); 
	   var fish_Mc:MovieClip = cast(appContainer_Mc.getChildByName("fish_Mc"),MovieClip); 
  	  mc =  new MovieClip() ;
 	  appContainer_Mc.addChild(mc);, 255 ,1);, mc.y); 
 	   fishWithCut_Mc.mask = mc ;
 	  addEventListener(Event.ENTER_FRAME, ef); 

public function ef(e:Event ) :Void 
{, mouseY); 

Sorted it out by replacing mask algorithm with bitmapData’s copypixel method. Works on mobile as well as desktop too.