Invoices with a "paid" status show on the Open Invoice Report. When viewing the payment, it is for less than the invoice total. No other payments are scheduled, no Credit Memos are applied and there are no discounts.
When reviewing the open invoice report there are many items that can cause open balances to show when after the record has been paid. To be sure we are reviewing an accurate report please make sure we review the steps in Open Invoice Report is incorrect.
If the invoice is still showing paid in this report Contact Support and reference this article.