UrlFetch from Google sheet exportLink ['application / pdf'] does not return PDF data

I am creating and sending a periodic email as an update from a Google Sheet. For various reasons, the customer is done in three ways, as a reference to the sheet, and as an attachment ( PDF

and XLSX

).

This worked quite recently. The XSLX application is still running, but the PDF is no longer sent as a response to UrlFetch

a URL file.exportLinks('application/pdf')

. No matter the request headers are always returned asContent-Type: "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"

Has anything else, undocumented, missing here changed?

function exportAsPDF(spreadsheetId) {
  spreadsheetId = spreadsheetId || 'SECRET_ID';

  var file = Drive.Files.get(spreadsheetId),
      url = file.exportLinks['application/pdf'];

  url += '&format=pdf&size=7&fzr=true&portrait=true&fitw=true&gid=0&gridlines=false&printtitle=false&sheetnames=false&pagenum=UNDEFINED&attachment=true'

  var token = ScriptApp.getOAuthToken(),
      response = UrlFetchApp.fetch(url, {
          headers: {
              'Authorization': 'Bearer ' +  token
          }
      });

  var headers = response.getAllHeaders(); // revealing content-type returned isn't pdf
  var pdfBlob = response.getBlob().getAs('application/pdf');      
  var pdfString = pdfBlob.getDataAsString(); // this naturally throws an error

  return response.getBlob(); // this returns to the send mail script
}