Purchase Plus has made changes from June 2020 onward to Paperless, or ePDF Invoices.
When the Invoice is sent to the Customer's Purchase Plus email address by a Supplier, enabled as a Paperless Supplier, in an ePDF Invoice, Purchase Plus will populate all fields of the Invoice, as below.
When the Invoice is sent to the Customer's Purchase Plus email address in a scanned PDF form, only these fields will be populated: Invoice number, Invoice Date, Purchase Order Number, Tax Total, Invoice Total. Line item value summary will be displayed as one line each for taxable and non-taxable goods.
For more information, please check out this article, ePDF Invoices explained.
There may also be an issue with how the ePDF was generated. Please contact Purchase Plus support to have a look at the Invoice, and correct it if required.