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

Commencez par exécuter la reproduction Python fournie avec plotly.offline.plot et la configuration modeBarButtonsToAdd, en la comparant à une liste de boutons vide. Suivez la génération du HTML hors ligne et vérifiez que la sortie s’affiche correctement avec les boutons de dessin activés ; utilisez l’environnement Python 3.7 et Plotly 4.14.1 indiqué lors de la vérification du comportement.