Path: WooCommerce > PDF Invoices > Advanced > Settings > Pretty document links.
If the Pretty document links setting is active, the WordPress permalinks should not be set to ‘Plain‘ at Settings > Permalinks.
If ‘Plain‘ is selected, a 404 error or a silent error may occur – redirecting to the wrong page – when trying to download or view a PDF.
Result – as a redirection to a wrong page:
