openpyxl merged column is not centered

I'm trying to center a text along a merged column. I saw some examples and saw this was the way

ws.merge_cells('A1:Q1')

ws['A1'] = tableTitle

title_cell = ws['A1']
title_cell.font = bold_font
title_cell.fill = title_fill
title_cell.alignment = title_alignment

the result I get is not centered at all.

The following code will do as you are attempting

import openpyxl
from openpyxl.styles import Font, PatternFill, Alignment

xlfile = 'foo.xlsx'
tableTitle = '3-Month Forecast Report starting 2024-09-19'
bold_font = Font(bold=True)
title_fill = PatternFill(start_color='90B4E2', end_color='90B4E2', fill_type='solid')
title_alignment = Alignment(horizontal='center', vertical='center')

wb = openpyxl.load_workbook(xlfile)
ws = wb.active

ws.merge_cells('A1:Q1')

ws['A1'] = tableTitle

title_cell = ws['A1']
title_cell.font = bold_font
title_cell.fill = title_fill
title_cell.alignment = title_alignment

wb.save(xlfile)