I just made a new Godot project and created a Label with text. Even with Align: center the text stays top left when I run the game.
Label.tscn
[gd_scene format=2]
[node name="Label" type="Label" index="0"]
anchor_left = 0.0
anchor_top = 0.0
anchor_right = 0.0
anchor_bottom = 0.0
margin_right = 40.0
margin_bottom = 14.0
rect_pivot_offset = Vector2( 0, 0 )
rect_clip_content = false
mouse_filter = 2
mouse_default_cursor_shape = 0
size_flags_horizontal = 1
size_flags_vertical = 4
text = "heylab"
align = 1
valign = 1
percent_visible = 1.0
lines_skipped = 0
max_lines_visible = -1
_sections_unfolded = [ "Anchor" ]