EventSystem IDragHandler not working on iOS

I cannot figure out why this doesn't work. I'm trying to use the EventSystem to detect Drag events on a GameObject on iOS. Everything works fine in the Editor with a mouse. I have implemented OnBeginDrag, OnDrag, and OnEndDrag as shown in the DragPanel script below. The script is attached to a cube. The cube also has a Box Collider, an Event System, and a Standalone Input Module. The camera has a Physics Raycaster attached. What am I missing? Thanks in advance.

 using UnityEngine;
 using UnityEngine.EventSystems;
 
 public class DragPanel : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler 
 {
     public Material material;
 
     public void OnBeginDrag(PointerEventData eventData)
     {
         Debug.Log("OnBeginDrag started ................................" + eventData.pointerCurrentRaycast.worldPosition);
         material.color = Color.blue;
     }
 
 
     public void OnDrag(PointerEventData eventData)
     {
         Debug.Log("OnDrag called ................................" + eventData.pointerCurrentRaycast.worldPosition);
         material.color = Color.blue;
     }
 
 
     public void OnEndDrag(PointerEventData eventData)
     {
         Debug.Log("OnEndDrag called ................................" + eventData.pointerCurrentRaycast.worldPosition);
         material.color = Color.white;
     }
 
 }