problem with colorbar LaTeX title rendering

I am trying to implement a LaTeX math title for my colorbar and plotly is having some trouble rendering it. I am using Python 2.7, Plotly 4.5.2. My code:

fig = go.Figure()
fig.add_trace(go.Scatter(x=x_data, 
                         y=y_data,
                         mode='markers',text=obj_name,name='',
                         marker=dict(symbol='circle',size=12,line=dict(width=1,color='SlateGray'),
                                     opacity=0.75,color=log_mbh,colorscale='Rainbow',showscale=True,
                                     cmin=6.0,cmax=8.0,
                                     colorbar=dict(title=dict(text=r'$\Large\alpha\beta\gamma\delta$',side='top'),
                                                   thickness=50,tickmode='array',tickvals=[6.0,6.5,7.0,7.5,8.0]), 
                                    ),
                         )
             )
fig.add_trace(go.Scatter(x=np.arange(0,300,10), y=np.arange(0,300,10),
                         line = dict(color='LightSlateGray', width=2, dash='dash')))

fig.update_layout(
    template='plotly_white',
    xaxis = dict(showgrid=False,ticks='inside',zeroline=True,zerolinecolor='black',rangemode='tozero'),
    yaxis = dict(showgrid=False,ticks='inside',zeroline=True,zerolinecolor='black',rangemode='tozero'),
    xaxis_title=dict(text=r'$x$'),
    yaxis_title=dict(text=r'$y$'),
    font=dict(size=16),
    showlegend = False,
    autosize   = False,
    width      = 750,
    height     = 750,
    margin     = dict(l=50,r=50,b=50,t=50,pad=10),
)

fig.show()

Which produces the output:

As you can see, the LaTeX title seems to be rotated 90 deg, and ignoring side='top'. I have tried to increase the width of the colorbar and increase the plot's margins to no avail. Is there a workaround or solution for this problem?

Commencez par exécuter la reproduction fournie avec Python 2.7 et Plotly 4.5.2, puis suivez la manière dont le titre de la colorbar gère le texte LaTeX et side='top'. Le travail est terminé lorsque le titre est rendu avec le LaTeX demandé et l’orientation supérieure, sans affecter les autres titres de colorbar.