Bug / Crash Downgrade to 5.1 and Rope Particle attachment not work

[okculo]

Hello, I have working on a project where a rope attached to 2 different dynamic object. I build project at 5.5 but due to ios problems i downgrade it to 5.1 . Now Exacly same code ı used to attach object sometimes works sometimes not. Any help? 


private IEnumerator startingRope()
    {
        rope.GetComponent<MeshRenderer>().enabled = true;

        blueprint = ScriptableObject.CreateInstance<ObiRopeBlueprint>();
        blueprint.resolution = 0.5f;
        blueprint.path.Clear();
        blueprint.path.AddControlPoint(currentBasePoint.transform.position, -Vector3.one, Vector3.one, Vector3.one, 2f, 0.1f, 1, 1, Color.red, "start");
        blueprint.path.AddControlPoint(topPoint.transform.position, -Vector3.one, Vector3.one, Vector3.one, 2f, 0.1f, 1, 1, Color.white, "end");
      // blueprint.path.FlushEvents();

        yield return blueprint.Generate();
       
        rope.ropeBlueprint = blueprint;
        ObiParticleAttachment[] attacher;
        attacher = rope.GetComponents<ObiParticleAttachment>();
        attacher[0].target = currentBasePoint.gameObject.transform;
        attacher[0].particleGroup = blueprint.groups[0];
        attacher[1].target = topPoint.gameObject.transform;
        attacher[1].particleGroup = blueprint.groups[1];



    }




rope sometimes fall to ground sometimes only start work sometimes both work. Couldnt solve the problem here. Unity 2019.3.7f1

My objects have collider and obi collider
   
   
   
falls toward void