Kivy AnchorPoint is not in the right place

I am trying to just put a piece of text centred in the top on the window but it ends up truncated in the bottom left.

I have the following python code:

# anchortest.py

from kivy.app import App
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.widget import Widget

class Root(Widget):
    pass

class TextTitle(AnchorLayout):
    pass

class AnchorTestApp(App):
    def build(self):
        return Root()

AnchorTestApp().run()

and it's associated kv file.

# anchortest.kv

<Root>
    TextTitle:

<TextTitle>
    anchor_x: 'center'
    anchor_y: 'top'

    Label:
        id: score
        text: 'Hello World'
        font_name: 'Courier New'
        font_size: 40
        pad_x: 10
        pad_y: 10

When I run the app I get this:

Don't use AnchorLayout for this case, just use BoxLayout with

pos_hint: {'top': 1}
size_hint_y: None

from kivy.app import App
from kivy.lang.builder import Builder

KV = """   
Screen:
    BoxLayout:
        orientation: 'vertical'
        
        BoxLayout:
            pos_hint: {'top': 1}
            size_hint_y: None
            
            canvas.before:
                Color:
                    rgba: [0.5, 0, 1, 1]
                    
                Rectangle:
                    pos: self.pos
                    size: self.size
            
            Label:
                text: 'Hello World'
                font_size: sp(60)
                
        BoxLayout:
            Label:
                text: 'Screen text'
"""


class TestApp(App):
    def build(self):
        return Builder.load_string(KV)


TestApp().run()

You also can use Label parametrs valign and halign:

KV = """   
Screen:
    Label:
        text: 'Hello World'
        font_size: sp(60)
        text_size: self.size
        halign: 'center'
        valign: 'top'
"""

> In order to control sizing, you must specify text_size to constrain
> the text and/or bind size to texture_size to grow with the text.

If you really want to use AnchorLayout for some reason, it's done this way. Following the kivy documentation, in order for the AnchorLayout rules to apply, the Label must be set with

size_hint_y: None
height: self.height

> The size_hint is a tuple of values used by layouts to manage the sizes
> of their children. It indicates the size relative to the layout’s size
> instead of an absolute size (in pixels/points/cm/etc)

KV = """ 
AnchorLayout:
    anchor_x: 'center'
    anchor_y: 'top'
            
    Label:
        text: 'Hello World'
        font_size: sp(60)
        size_hint_y: None
        height: self.height
"""