Are you trying to report on "Never Validated" invoices in Oracle? Or have you noticed that some invoices are missing from the "AP_INVOICE_DISTRIBUTIONS_ALL" table and wondered what’s going on?
A new feature has been introduced in Oracle EBS R12 where imported AP Invoices are not saved to the invoice distributions table until a user has manually saved the imported invoice. This feature was created to provide the user the opportunity to review the distributions before they are committed to the table.
The user will be able to see the unsaved distributions in the normal distributions form but will notice the distribution class showing as "Preview" rather than "Saved." Unfortunately this new feature has caused a number of issues when trying to report on "Never Validated" invoices or for reporting that is based on the Invoice distributions table.
The Oracle recommended workaround is to run "Invoice Validation" after the import to save the distributions, unfortunately this means you lose the ability to review the transactions before they are validated.
Perhaps a better workaround would be to use the "Hold Name" parameter on the “Payables Open Interface Import” process to add a manual hold and then run "Invoice Validation." This way the imported invoices will not get validated due to the hold but will still be saved and give you the ability to report as well as review.
Taking this one step further you could add a new Manual hold type to make it easy to identify imported invoices that had not yet been reviewed. Here's a hyperlink to the AP document to review: Imported Invoices Show Distribution Class Of Preview (Doc ID 1174013.1).