Missing Reference Exception

Hi, I'm having an issue with my enemy lists where if a group is empty it will still run through the for loop causing a missing reference exception and not spawning a new group. I think it's not removing the empty list but I can't seem to figure out why it isn't.

I wasn't having this issue before when I had the for loop as

 for(int j = enemyGroupList.Count - 1; i>=0; i--)

This was throwing an argument out of range exception and wasn't what I needed there but it would update the groups properly and spawn a new one when needed.

 void Update () {
     if(enemyGroupList.Count < groupNumber)
     {
         enemyGroupList.Add(createGroup());
     }
 
     // for each list in the group list
     for(int i = enemyGroupList.Count - 1; i >= 0; i--)
     {
         // for each opject in a given list
         for (int j = enemyGroupList[i].Count - 1; j >= 0; j--)
         {
 
             // pause and unpause enemies when the player pauses the game or is talking
             if (player.CurrState == PlayerScript.State.Paused || player.CurrState == PlayerScript.State.Talking)
             {
                 enemyGroupList[i][j].enabled = false;
             }
             else
             {
                 enemyGroupList[i][j].enabled = true;
             }
 
             // remove dead enemies
             if (enemyGroupList[i][j].Dead)
             {
                 enemyGroupList[i].RemoveAt(j);
                 // break avoids out of range exceptions
             }
         }
         if (enemyGroupList[i].Count == 0 || player.CurrState == PlayerScript.State.Win)
         {
             enemyGroupList.RemoveAt(i);
         }
     }
 }
 

Thanks