Why would they be missing?

Incorrect backup and restore procedures could result in transactions being in AR but not Invoices. Or, you have purged the fully paid transactions from Receivables duing a period end - this doesn't remove them from Invoices.

Here's a method to create this list.

• In Smartfinder (F6), add the LAST YEAR Invoices, Adjustments, Credit note figures to the grid.
• Select all customers (cust # <> blanks)
• ExcelDirect the list
• Calculate the net sales in Excel
• Sort the list in descending order in Excel
• Save the top 10 customers
• Delete all but the top 10 customers
• Delete all columns but the customer number
• Save the resulting sheet as Top10.xls
• Go back to Adagio Receivables
• Create an import template (File | Import | Customers) that imports from Top10.xls, just the customer numbers, without adding new records, but allowing Overwrite, with a title row.
• Specify that the customer number is being imported
• Set the field "Report Group" to default to "Top10" on import
• Import the sheet
• Run the report for just the report group "Top10"

It's probably taken me longer to write the list of steps that it will take you to complete the process.