Hi, Ng1234QK
Welcome to the Microsoft community.
Regarding the issue with Edge PDF browsing, you can first try switching to a different Edge PDF Viewer to see if it resolves your problem.
edge://flags/#edge-new-pdf-viewer
After that check the PDF settings in Edge.
edge://settings/content/pdfDocuments?search=pdf
You can also try using different versions of Edge to see if that works.
Become a Microsoft Edge Insider | Microsoft Edge
If none of these solutions work, I recommend using Edge's feedback feature (Alt+Shift+I) to report the issue you're experiencing.
Best regards
Tommy Jin | Microsoft Community Support Specialist