Taxes question – 1099k not matching summary for the year

Does anyone know why my summary sheet for the year, (pulled under the payments section of reports), does not match my 1099k?

The 1099k is showing $18,000 more than my Amazon summary report. When I contacted Amazon help they said this was probably customer returns. When I pull the entire transaction report excel sheet and add up the returns it’s $9,000, so that still doesn’t add up. How do I account for this extra $18,000 showing up on my 1099k? It’s always been a little off, but never like this.

Thank you.