Python Pandas xlsxriter stacked line chart type setting standard line chart in Excel

I am trying to created stacked line charts in excel using pandas and xlsxwriter.

When entering the chart type dict into add chart I use what the documentation states should configure a stacked line in Excel. (So I think anyway!) When I open Excel I get a standard line chart, which means I need to manually change to stacked line (the second across box)

Here's some example code

import pandas as pd

# example csv data
'''
Date-Time   col1    col2
2021-03-01 00:00:00 34329   34540
2021-03-01 00:15:00 34174   34369
2021-03-01 00:30:00 34121   34418
2021-03-01 00:45:00 34012   34235
2021-03-01 01:00:00 33959   34273
2021-03-01 01:15:00 33825   34049
2021-03-01 01:30:00 33782   34010
2021-03-01 01:45:00 33584   33882
2021-03-01 02:00:00 33601   33905
2021-03-01 02:15:00 33415   33746
2021-03-01 02:30:00 33412   33827
2021-03-01 02:45:00 33291   33744
2021-03-01 03:00:00 33329   33816
2021-03-01 03:15:00 33209   33745
2021-03-01 03:30:00 33219   33833
'''

# create df
with open('example.csv', 'r') as csv:
    df = pd.read_csv(csv).set_index('Date-Time')

# Create the workbook to save the data within
workbook = pd.ExcelWriter('example.xlsx', engine='xlsxwriter')

# Create sheets in excel for data
pd.DataFrame().to_excel(workbook, sheet_name='Dashboard')

# assign a blank dashboard for the charts
worksheet_dashboard = workbook.sheets['Dashboard']

# Get the xlsxwriter objects from the dataframe writer object
# for use with creating charts later
book = workbook.book

# Create sheets in excel for data
df.to_excel(workbook, sheet_name='example')

# Add the line chart objects
chart = book.add_chart({'type': 'line', 'subtype': 'stacked'})

# Configure the first series.
chart.add_series({
    'name':       '=example!$B$1',
    'categories': '=example!$A$1:$A$16',
    'values':     '=example!$B$2:$B$16',
})
chart.add_series({
    'name':       '=example!$C$1',
    'categories': '=example!$A$1:$A$16',
    'values':     '=example!$C$2:$C$16',
})

# Insert the chart into the worksheet 
worksheet_dashboard.insert_chart('A1', chart)

workbook.save()

You can see that the line

# Add the line chart objects
chart = book.add_chart({'type': 'line', 'subtype': 'stacked'})

Should provide the type as line and subtype stacked, anyone encountered this problem before?

As a note the versions I'm using:

• Microsoft Office 365 Excel version 2008.
• print(pd.version) outputs: 0.23.0