Why is Calc failing to sort a column of numbers?

I have a column of numbers that is 80 rows deep. When I sort them ascending, they sort fine with the exception of rows 70 to 75. The numbers in rows 70 to 75 go to the bottom of the sort and regardless how many times I sort they stay there (at the bottom). I have other columns with a heck of a lot more rows of numbers (one in particular has close to 700) and it sorts perfectly.

Why? What am I doing wrong?

Thanks in advance and regards from Ottawa, Canada.

The numbetrs may be text looking like numbers. Did you try ‘View’ > ‘Value Highlighting’? Yoi may also use the functions ISTEXT and ISNUMBER.