Create scatter plot from someone else’s data

I have latitude and longitude data in a spreadsheet from another source. If I highlight the 2 columns of data and insert scatter plot, it takes one number from column 1 (the last number in the column) as the Title for the plot (highlights the value in red on the spreadsheet) and enters data equal to the length of the second column as (1,0) (highlighted in blue on the spreadsheet. If I enter the numbers manually into 2 columns and do the same thing, they are displayed correctly. I’ve tried copying and all possible options for pasting witho0ut any positive effect. I tried formatting the cells as “Numbers” (they are incorporated as “General” in the source spreadsheet) without positive effect. I’ve tried copying and pasting into a new spreadsheet (not just a new sheet) without positive effect. What am I doing wrong?