I have integrated an SAP CAP application with Ariba through punchout. At the end of this process, I create a Purchase Requisition as a result of the user’s cart. The issue arises when I try to attach a generated PDF containing the cart’s products to the requisition import SOAP web service; the attachment is always blank.

Steps Taken:

I generate the PDF using pdf-lib.
I include the generated PDF in the tag of the SOAP request.

Expected Outcome:
The PDF should be correctly attached and contain the list of products from the cart.

Actual Outcome:
The attached PDF in the successfully created PR in Ariba is always blank.

Code Snippet:
Here is the relevant code snippet:

const pdfDoc = await PDFDocument.create();
const page = pdfDoc.addPage([600, 400]);
page.drawText('Product list and details', { x: 50, y: 350 });

const pdfBytes = await pdfDoc.save();
const pdfBase64 = Buffer.from(pdfBytes).toString('base64');

// SOAP request snippet
const soapRequest = '
<urn:Attachments>
<urn:item>
 <urn:Attachment>
<urn:Filename>Options.pdf</urn:Filename>
<urn:ContentType>application/pdf</urn:ContentType>
</urn:Attachment>
<urn:ExternalAttachment>true</urn:ExternalAttachment>
<urn:MappedFilename><xop:Include xmlns:xop="http://www.w3.org/2004/08/xop/include" xop:contentType="application/pdf" href="cid:Options.pdf">${pdfBase64}</xop:Include></urn:MappedFilename>
</urn:item>
</urn:Attachments>';

const options = {
    url: '/forwardRequest',
    method: 'POST',
    data: soapRequest,
    headers: {
        'Content-Type': 'text/xml;charset=utf-8',
        'SOAPAction': '/Process Definition',
        'type': 'application/xop+xml'
    }
};
$.ajax(options)
    .done(function (response, statusText, xhr) {
        debugger;

        if (xhr.status == 200) {
            console.log('Raw result', response);
        };
        console.log('Message', xhr.status, statusText);
    })
    .fail(function (error) {
        console.error('Error', error.status, error.statusText);
    });

Additional Information:

The integration between SAP CAP and Ariba is working fine for other functionalities.
The PDF generation process using pdf-lib works correctly when tested independently.
The SOAP web service call succeeds, but the attachment remains blank.