Error ModelTargetBehaviour.ModelTarget on iOS

Hi,

I created the app that using model target and i managed to create a button to change the current guide view. The app works perfectly while i am working on PC and tested on Android.

But when i open the project on Mac and tested on Iphone, the apps has a bug. I checked it and found out the ModelTargetBehaviour.ModelTarget reference is null. In editor, database and model target in ModelTargetBehaviour gameobject is set correctly even in Play Mode, it is not Empty.

This is my script to access the model target.

private ModelTargetBehaviour _modelTargetBehaviour;

private void Start()
{
 _modelTargetBehaviour= GetComponent<ModelTargetBehaviour>();
}

public void GuideView(int toggleId)
{
 if (_modelTargetBehaviour!= null)
 {
  ModelTarget modelTarget = _modelTargetBehaviour.ModelTarget;
  modelTarget.SetActiveGuideViewIndex(toggleId); //here is the error but only on iOS, modelTarget is null reference
 }
}