How to delete an idr scanned invoice matched to a purchase order

We scan invoices using IDR, and sometimes realize the wrong PO is automatically matched because the pdf is incorrect. We need to delete this invoice so we can re-scan the pdf with the right PO number. The invoice is still in incomplete status, so we highlight the invoice and click on the 'X', a window pops up confirming we want to delete the record, and then nothing happens. The invoice still appears in the Scanned tile even when I refresh the dashboard. How do we delete these invoices?