How to extract Ap invoices for which attachment is not available

Summary:

I want to extract the all AP invoices for which users has not upload the attachment.

Below mention REST API is not working but when I changed the "And attachments.FileName is not null" then it is successfully return the invoices for which attachment is available.

Content (please ensure you mask any confidential information):

https://server/fscmRestApi/resources/11.13.18.05/invoices?expand=attachments&onlyData=true&fields=InvoiceType,InvoiceId,InvoiceNumber,InvoiceCurrency,InvoiceDate,InvoiceAmount,Supplier,SupplierNumber,SupplierSite,CreationDate;attachments:FileName&q=CreationDate >='2025-10-16' And SupplierSite IN('80377','8023','8013') And InvoiceType IN('Standard','Credit memo') And attachments.FileName is null