Procurement- PO matched invoice missing from PO invoice list

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I am trying to submit a change order to update the Billing and Project Details for a PO and am getting an error stating that I can’t submit a change order because there is (approx) $7,000 matched to it. However, when I look at the Order Life Cycle details page all the invoices listed show that they are unmatched. I searched invoices for this suppler but was not able to find any additional invoices matched to this PO. Any guidance on how to find which invoice is causing this error is appreciated. Thanks! 

Screenshot is from an export of the invoices listed in the Order Life Cycle page.