I was shocked when I imported a 1.5M row dataset into Office365 Excel and found that it had silently cropped my data to 1048576 rows. One million items is a ridiculously low limit for a modern computer, and deleting 1/3 of my data without any warning is unacceptable. 20 years ago Excel could handle 1.5 million rows without breaking a sweat but this webpage version isn't real Excel.
So I used Gnumeric instead and it worked fine.