Resolved -
We would like to let you know that we have implemented our own solution for this problem. The PDF viewer has now been updated to an embeddable version.
Please note that with this new player, there is no native support for downloading or printing files. To ensure everything works smoothly, we recommend clearing your cache and cookies before testing the updated viewer.
Thank you for your understanding and patience!
Apr 15, 10:00 CEST
Identified -
We are aware of an issue regarding PDF files failing to display in a Course. We can confirm this is related to a known bug in SharePoint, and Microsoft is actively working to resolve the issue. You can follow the discussion via the URL below. We will continue to update our status page as relevant information becomes available. https://github.com/SharePoint/sp-dev-docs/issues/10180
Apr 3, 17:50 CEST