Hi, 

When you process the interest proposal (reminders work similar) IFS updates the invoice record to include the last date of interest calculation.  Because you successfully created the interest, that interest included a calculation (as of) type date. When you run the process again, IFS will not select the same invoice for the same date range multiple times. 

The data (last interest date) is editable by a user, so you can edit the date and set this back to the last time the interest was correct.  

In the above example, I had an interest calculation date of September 2021.  As a user I essentially told IFS to recalculate the interest back to the original due date. 

Assuming a large number of invoices, because the data is user editable, you can use external files or a migration job to export the data, edit in excel and load back in.  I believe I did this for a client a good number of years ago. 

If you know the affected invoices the update is pretty easy. 

Try a sample invoice and set the date manually then run a new interest proposal just to select the invoice and see the interest calculation.  You don’t need to complete the process.   Once you know this works as needed and the calculations are now correct, you can plan to update the related invoices. 

Best regards