Sprite Animation isn't showing up on screen, while being visible in debug C#

Godot Version

Godot 4.1.3

Question

I’m spawning monsters from a packedscene :
dungeonMonster = monsterScene.Instantiate();
_monster = dungeonMonster;
and then later on spawning them based on points:
Random r = new Random();

    var points = this.GetChildren();
    int monsterHealth = r.Next(1,MonsterPower + 1);

    SpawnMs();
    AddChild(_monster);
    foreach (Node point in points)
    {
        
        base_dungeon_monster monsty = new DungeonMonster()
        {
            _animSelector = _monster._animSelector.Duplicate() as AnimatedSprite2D,
            _animSprite = _monster._animSprite.Duplicate() as AnimatedSprite2D,
            _col = _monster._col.Duplicate() as CollisionShape2D,
            _hp = _monster._hp,
            _monsterHighlightImage = _monster._monsterHighlightImage.Duplicate() as Sprite2D,
            _monsterImage = _monster._monsterImage.Duplicate() as Sprite2D,
            _label = _monster._label
        };

        var tempMonster = monsty;

        var p = (Marker2D)point;
        AddChild(monsty);
       //mapping resources in order to get a deep clone
        MapCorrectResources(monsty, tempMonster);

        if (_listOfMonsters[listIndex].GetParent() == null)
        AddChild(_listOfMonsters[listIndex]);

        monsty.Position = p.Position;
        monsty.Connect("MonsterWon", new Callable(_player, "_OnMonsterWon"));
        monsty.Connect("MonsterVanished", new Callable(_player, "_OnMonsterVanished"));
        monsty.Show();
        monsty.ZIndex = 2;
        monsty._hp = monsterHealth;

}}

first only 1 monster is spawned, secondly the mouse over works, as in it enters the the _on_mouse_entered function (writes output and while debugging the animations are visible and playing):
public void _on_mouse_entered()
{
// _animSprite.Animation = “Die”;
this._monsterImage.Visible= false;
this._monsterHighlightImage.Visible = true;
this._animSelector.ZIndex= 2;
this._animSelector.ShowBehindParent = false;
this._animSelector.Show();
this._animSelector.Visible = true;
this._animSelector.Animation = “selected”;
this._animSelector.Play();
GD.Print("anim selector id: " + this._animSelector);
this._animSprite.Visible = false;
GD.Print("entering moster in position: " + this.Position);
this._animSelector.MoveToFront();
_onMonster = true;
}

but visually (on the screen) the animations aren’t showing up.

what am I doing wrong?

Hard to say from your code, and description is not clear for me what really going there. You can delete all ‘this’ form your code. look your objects in remote tree.
What you trying animate? who call public void _on_mouse_entered()? try first make simple working code before add all extras.

the _on_mouse_entered() is a signal that is on the monster to catch a mouse over (which works). The monster is an area2d, with a signal attached to the collisionobject2d.
I have a selector that should show up and play, but nothing happens besides writing outputs:
public void _on_mouse_entered()
{
//hiding the main sprite
_monsterImage.Visible= false;
//making sure the animation (AnimatedSprite2D) is on top
_animSelector.ZIndex= 2;
//making the animation visible
_animSelector.Show();
_animSelector.Animation = “selected”;
_animSelector.Play();

    GD.Print("entering monster in position: " + Position);
} //simplified? code 

all this was working before. The id of the animation is the same when spawning the monster and when the signal is triggered, and like I said before outputting it shows that the animation is visible, the right animation is selected and is it playing (frames change), but visually nothing happens.

another thing to add, that in the nodetree (remote) I can toggle the visibility of the animation (of that specific monster node) and that works.