Hi Bart,
Thank you for contacting Syncfusion support.
On further analyzing the given Word document, we have found that embedded Word document is used as EMF image. Currently, the metafile images (*.wmf, *.emf) in Word document are not supported while converting to PDF in Azure environment which is already a known limitation. We have considered this exception problem at our end and will provide fix to skip the exception to convert the given Word document as PDF. This fix will be included in our 2018 Volume 4 SP1 release which is expected to available at the end of January 2018 tentatively.
Please refer the below KB to know more about known limitation Azure environment while converting Word document as PDF:
Regards,
Prakash Kumar