This also happened to my installation of Office 2016 on the same date.
Microsoft® Word 2016 MSO (Version 2310 Build 16.0.16924.20054) 64-bit

I can provide an examples of the PDF file produced on October 29 having correct relative links, while a PDF file generated from the same DOCX source after November 1 has all fullly-qualified links in the PDF.

This is especially bad for producing PDF files, since all the formerly relative links in a large document are now fully qualified.
I also just found that newly-added hyperlinks in the DOCX file become fully qualified when rendered in HTML, while earlier untouched links remain as relative in the HTML.

I have Word 2010 available, so I can use it for now, but no longer having relative links is actually crippling to my requirements.