You may receive the exception error: Your invoice has 1099 information. Do you want to mark the vendor as a 1099 vendor? when committing invoices in FAST! although there may not be any 1099 information in the FAST! datasheet.
The original saved FAST! data sheet had 1099 fields that were removed and may be causing the exception, create a new FAST! data sheet:
In FAST! click New AP invoice button to create a new datasheet without any 1099 fields