BeginGroup not acting the same on iOs and on Android.

Hello community!

I had a lot of help by reading your answers here, but I'm facing a problem, and I can't figure a solution:

On Android, I have a lifebar, made with boxes in a Begin/EndGroup. It works fine, but when I build my game on iOS, it looks weird, showing only a part of it. Everything else works fine from the porting to iOs, Boxes, Screen.width related stuff... It's just that. You can see it below, and the code too.

 function L(){
 return (Screen.width*1.001);
 }
 
 function H(){
 return (Screen.height*1.001);
 }
 private var pos : Vector2 = new Vector2(L()/8.7,H()/28);
 private var size : Vector2 = new Vector2(L()/3.5,H()/12);
 
 // draw the background:
     GUI.BeginGroup (new Rect (pos.x, pos.y, size.x*1, size.y*1));
         GUI.Box (Rect (0,0, size.x*1, size.y*1),progressBarEmpty);
 
         // draw the filled-in part:
         GUI.BeginGroup (new Rect (0, 0, size.x*1 * barDisplay, size.y*1));
             GUI.Box (Rect (0,0, size.x*1, size.y*1),progressBarFull);
         GUI.EndGroup ();
 
     GUI.EndGroup ();

Does anyone has an idea of what is happening there? Thanks in advance,

PJ