Using Coroutines and OnGui Together

I'm looking for a better way to partner Coroutines and OnGUI. The following example works but not well (button clicks get missed and stop working after a while), so I'm wondering if there is any different way to design this:

 using UnityEngine;
 using System.Collections;
 
 public class LatentController : MonoBehaviour {
 
     public int Count = 0;
     bool UserInput=false;
     IEnumerator TestInput()
     {
         while (true)
         {
             if (!UserInput)
             {
                 Debug.Log("Round: "+Count);
 
                 //do any calculations until we need more user input
 
                 UserInput = true;
             }
             if (UserInput)
             {
                 yield return new WaitForEndOfFrame();
             }
         }
     }
 
     void OnGUI() 
     {
         if (UserInput)
         {
             if (GUI.Button(new Rect(10, 10, 150, 100), "Reset"))
             {
                 UserInput = false;
                 Count=0;
             }    
             if (GUI.Button(new Rect(10, 120, 150, 100), "Continue"))
             {
                 UserInput = false;
                 Count++;
             }
         }
     }
 
     // Use this for initialization
     void Start () 
     {
         StartCoroutine(TestInput());
     }
 
 }