VR Selection of buttons only works once unless scene refreshed.

This is my first question on this forum, so apologies if I haven't got the etiquette right.

Unity Version: 2019.4.21f1

Using Unity, I'm working on a very basic VR project (for Android devices) and on the UI there are a number of buttons that when selected open up dialogue boxes with additional information (instructions etc). These buttons are selected using a ray interactor. I have scripts to open and close the dialogue which all work the first time.

The ray interactor has a red dot that gives the user a reference point and when selecting the buttons there is a gazecircle for 2 seconds before the dialogue box appears/ disappears.

The issue is that I can open and close a dialogue boxes the first time in the scene but they will not open a second time unless I exit and reenter the scene. However the gaze circle still works

Any help would be gratefully received.

The code is as below (which has been adapted from code on a Youtube tutorial):

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class popUpHealthOpen : MonoBehaviour
 {
     public GameObject healthWarnPanel;
     public Image gazeCircle;
     public float totalTime = 2;
     bool gvrStatus = false;
     public float gvrTimer = 0;
     void Start()
     {
         gazeCircle.fillAmount = 0;
     }
 
     void Update()
     {
         if (gvrStatus)
         {
             gvrTimer += Time.deltaTime;
             gazeCircle.fillAmount = gvrTimer / totalTime;
         }
 
         if (gvrTimer > totalTime)
         {
             gazeCircle.fillAmount = 0;
             healthWarnPanel.SetActive(true);
         }
     }
     public void OnPointerEnter()
     {
         gvrStatus = true;
     }
     public void OnPointerExit()
     {
         gvrStatus = false;
         gvrTimer = 0;
         gazeCircle.fillAmount = 0;
     }
 }