We apologize for the inconvenience caused, as per the description above, you are not able to export a PDF file using the Adobe ExportPDF service, Is that correct?
Please try exporting the PDF document using the URL https://cloud.acrobat.com/exportpdf with your Adobe ID and password on a different browser like Chrome or Firefox, or Safari and see if this brings any difference.
If you are using the free desktop version of Adobe Reader DC and facing issues, please sign out and sign back in with your current Adobe ID and password in Adobe Reader DC and check for any pending updates of Adobe Reader from Help>Check for updates.
For more troubleshooting, you may refer to Troubleshooting Create PDF, Export PDF, Adobe Send, Fill & Sign … services(PDFPack or Document Cloud...
Let us know how it goes.