Problem with collider transform inside coroutine, with collider attached to a bone

Hi folks. I am trying to implement a slider control that can be interacted with using a virtual finger (attached to a hand controlled by a razer hydra).

I've simplified here for illustration but basically I want to select a slider/button (sphere) with a finger tip and draw a line between the finger tip and the slider control. I then want to update the line as the hand moves around so it always connects the fingertip and the control.

If I do this in a coroutine CheckControl(), the line is drawn from the slider to an OFFSET position where the fingertip WAS when the scene first starts (i.e. when in T-pose).. if I move the entire humanoid, the line updates but always connects off to the side instead of where the fingertip collider actually is when I move the hands around (as though the collider is parented to the humanoid root bone instead of the finger tip bone). I can see the collider in the correct position on the fingertip in the scene view, but the line does not connect to it.

Can anyone shed any light on what I might be doing wrong?

Thanks

Simplified setup:

• Rigged humanoid model with IK rig for the arms, which are controlled using hydra controllers

• Empty object attached to an index finger, with a box collider and a rigidbody (no gravity)

• A sphere (slider control) that I want to trigger. With a sphere collider and trigger=true

• Script below attached to the sphere control (trigger)

• When OnTriggerEnter called, I get a reference to the collider (finger tip) that triggered the sphere and use that in the coroutine (or update) to draw a line between sphere and finger tip

Code:

 using UnityEngine;
 using System.Collections;
 
 public class SliderTest : MonoBehaviour
 {
     protected LineRenderer m_LineRenderer = null;
     protected Collider m_Collider = null;
     protected bool m_Active = false;
 
     void Start()
     {
         // create connection line
         m_LineRenderer = gameObject.AddComponent<LineRenderer>();
         m_LineRenderer.material = new Material(Shader.Find("Particles/Additive"));
         m_LineRenderer.SetColors(Color.blue, Color.green);
         m_LineRenderer.SetWidth(0.01f, 0.01f);
         m_LineRenderer.SetVertexCount(0);
     }

     protected IEnumerator CheckControl()
     {
         while (m_Active)
         {
            Debug.Log("m_Collider.transform.position " + m_Collider.transform.position);
 
            // draw connection line
            m_LineRenderer.SetVertexCount(2);
            m_LineRenderer.SetPosition(0, m_Collider.transform.position);
            m_LineRenderer.SetPosition(1, transform.position);
 
            yield return null;
         }
 
         m_Active = false;
     }
 
     void OnTriggerEnter(Collider obj)
     {
         Debug.Log("Triggered By: " + obj.tag);
 
         if (!m_Active)
         {
             m_Collider = obj;
             m_Active = true;
 
             StartCoroutine(CheckControl());
         }
     }
 }