Add GameObject to List by tag not working consistently

Hi Guys,
I am trying to do a very simple operation, which is adding GameObjects to a list with a specific tag, but its not working consistently across play mode. The following piece of code is in a Class which is a script attached to a Prefab.

//List to store Activated  PlaceHolders.
base.activatedPlaceHolders = GetActivatedPlaceHolders(base.placeHolderLocalList);    

  private List<PlaceHolder> GetActivatedPlaceHolders(List<PlaceHolder> placeHolderList)
        List<PlaceHolder> activatedPlaceHolders = new List<PlaceHolder>();

        foreach (var item in placeHolderList)
            if (item.gameObject.tag != "CollidedPlaceHolder") activatedPlaceHolders.Add(item);


        return activatedPlaceHolders;

The class PlaceHolder is attached to another Prefab. What I am trying to do is to add the PlaceHolders whose tag is not “CollidedPlaceHolder” to the activatedPlaceHolders List. But its not working consistently when the game is played and I am not sure why. The main goal is to ignore the place holders with such a tag.

Any help would be very nice!

Hi guys, I still could not figure this out and I have tried the same logic outside of unity and it works fine.

List<int> testList = new List<int>{1,76,3,4,5,76,76,8};
  public List<int> RemoveElementsB(List<int>testList)
    List<int> a = new List<int>();

    for (int i = 0; i < testList.Count; i++)
      if(testList _!= 76) a.Add(testList*);*_


return a;
This is a very straight foreword operation, the following method works fine, and I even tested it generating a list with the number 76 to reomove at every update call and It worked fine. So I am wondering why its not working consistently in Unity… Any help would be great, Thanks!