Flet Tabs: does it works correctly?

[Alitalia60]

Question

Flet Tabs are they works correctly?

flet --version
0.19.0

I test simple code
when I'll discommit lines with
# alignment=ft.alignment.center

contents of Tabs will not shown

WHY ??

Code sample

import flet as ft

def main(page: ft.Page):
    tab = ft.Tabs(
        selected_index=0,
        tabs=[
            ft.Tab(
                text="Tab item 1",
                content=ft.Container(
                    # alignment=ft.alignment.center,
                    content=ft.Text("container 1", color="black"),
                ),
            ),
            ft.Tab(
                text="Tab item 2",
                content=ft.Container(
                    # alignment=ft.alignment.center,
                    content=ft.Text("container 2", color="black"),
                ),
            ),
            ft.Tab(
                text="Tab item 3",
                content=ft.Container(
                    # alignment=ft.alignment.center,
                    content=ft.Text("container 3", color="black"),
                ),
            ),
        ],
    )
    page.add(tab)


ft.app(target=main)

Error message

No response

------------------------------------------------------

• I have searched for answers to my question both in the issues and in previous discussions.

[Alitalia60]

Tabs property
extend=True

helps me to solve problem