[BUG] dbc Tabs not showing default first tab anymore with Dash 4.2.0 and higher

For any Dash version > 4.1.0, the dash-bootstrap-components (dbc) Tabs do not show the default 1st tab anymore.

With dash==4.1.0 and dash-bootstrap-components==2.0.4

With dash==4.4.1 and dash-bootstrap-components==2.0.4

With the following trivial example:

from dash import Dash, html
import dash_bootstrap_components as dbc

app = Dash(__name__, title="Dash Tab Test", external_stylesheets=[dbc.themes.BOOTSTRAP])

children = [dbc.Tab(html.H2(f"Test Tab {i}"), label=f"Tab {i}") for i in range(3)]

app.layout = (
    html.Div(
        [
            dbc.Tabs(children=children)
        ]
    ),
)


if __name__ == "__main__":
    app.run(debug=True)

Note: if you switch on the tabs back and forth, the tab contents appear again. It's just the first tab does not show up anymore by default. See also dbc documentation.

Inizia con l’esempio Python minimo nell’issue e riproducilo con Dash 4.1.0 rispetto a 4.4.1 e dash-bootstrap-components 2.0.4. Traccia il rendering di Tabs e il comportamento della selezione predefinita; il lavoro è completato quando il contenuto della prima scheda appare al caricamento iniziale e il passaggio da una scheda all’altra continua a funzionare.