So, I just finished creating my design on XD for a school project. My instructor asked us to export our XD designs to PDF so we could incorporate them into InDesign process books without losing the vector quality of text and graphics. Unfortunately, when I exported my file to PDF, all my images, shapes, and any text that wasn't basic black got rasterized. I sent my instructor my XD file and he tried exporting to PDF and did not have the same issue. The only difference is that he's using a Mac and I'm on a Windows based system. XD doesn't seem to present any options for quality when exporting to PDF, so I'm not sure what's going on here.
I've attached two screenshots - one zoomed in to show the vector images on XD, and the other zoomed in to show how they got rasterized on PDF (but not the black text, oddly?)
Sorry to hear about the trouble. Will it be possible for you to share the file with us so that we can test this on our end? Also, I'd request if you can check if the Graphics card is up to date as per the manufacturer's website. To send the file, you can add the file to cloud storage and share the link here.