In Business Central (on-line,) when everything else is confirmed to be correct and you are still not getting correct amounts on your 1099-NEC, it may be because the Calendar Year field in the report request page is not working correctly.
The tool tip indicates the default for the Calendar Year in the 1099-NEC report request page is set using the work date year. This is correct, it is. However, even if you change the Calendar Year on the request page, it does not use this value. It continues to use the work date year.
To get your 2020 1099-NEC report with correct amounts, you must change your work date to one in 2020. I used 12/31/2020 to get the correct amounts. You can do this from Settings.
I am certain this is a bug, however getting it fixed and out there before you need to run the reports may not happen.