Browser keeps opening with auto_open=False in offline mode

I can plot a chart with nice lines, no issues but when I run my code I get the browser being opened even though I set auto_open=False:

layout = dict(title=‘Quantity by year’,
xaxis=dict(title=‘Months’),
yaxis=dict(title=‘Quantity’),
)

fig = dict(data=data, layout=layout)

offline.plot(fig, image='png', image_filename=chart_name, filename=file_name, auto_open=False)

What am I missing?

Thanks