Today I noticed some weird issue that for some reason last column in my file (and any test file I created with similar structure) is not being deleted with 'delete_cols()'. Any other column is deleted fine. The files I tested on Windows were created on Windows machines.
Code that I used for testing on both Windows and Mac:
wb = openpyxl.load_workbook('Test_data.xlsx') ws = wb.active ws.delete_cols(5) wb.save('Test.xlsx')
On Windows it simply does not change anything and on Mac it removes any column just fine.
I use Python 3.6.3 on Windows and Python 3.6.2 on Mac.