modeBarButtonsToAdd doesn’t appear to be working as intended

Using "modeBarButtonsToAdd" to add buttons for interactive annotations and shape drawing in plotly figures, it prevents the HTML plot to be shown at all with plotly.offline rendering!

import plotly.offline as offline
import plotly.express as px
df = px.data.iris()
fig = px.scatter(df, x='petal_width', y='sepal_length', color='species')
fig.update_layout(
    dragmode='drawopenpath',
    newshape_line_color='cyan',
    title_text='Draw a path to separate versicolor and virginica'
)

config = dict({'scrollZoom': True,'displaylogo': False, 'modeBarButtonsToAdd':['drawline','drawopenpath','drawcircle','drawrect','eraseshape']}) 

offline.plot(fig,  
                     auto_open=True, image = None, config =config, 
                     filename='./foo.html', include_plotlyjs='directory')

If the 'modeBarButtonsToAdd':[ ] is emptied, the HTML is correctly rendered again. Any idea with this weird behaviour?
Please, see also https://eoss-image-processing.github.io/2020/05/06/shape-drawing.html

Environment:
Python 3.7
Plotly 4.14.1
dash 1.18.1

Empieza ejecutando la reproducción proporcionada en Python con plotly.offline.plot y la configuración modeBarButtonsToAdd, comparándola con una lista de botones vacía. Traza la generación del HTML offline y verifica que la salida se renderiza correctamente con los botones de dibujo habilitados; usa el entorno indicado de Python 3.7 y Plotly 4.14.1 al comprobar el comportamiento.