OneDrive embedded PowerPoint slides showing blank page or error

Because all existing embeds, a new embed, and an unrelated presentation fail while a Microsoft resource returns 404, one file or your course HTML is unlikely to be the cause. Confirm each presentation opens in PowerPoint for the web and its sharing permission allows the intended audience. Generate the iframe only from PowerPoint for the web, then test it in a minimal blank page to exclude the learning platform’s content-security policy. Have a Microsoft 365 administrator check Health > Service health for OneDrive and Office for the web incidents, including issue history around the UTC time in Ref C. Preserve the reference values, failed request URL, tenant, browser, and timestamps. If direct viewing works but multiple minimal embeds still return the same Microsoft 404 and no advisory exists, report an issue from Service health or open a support case. Rebuilding every course or presentation is not justified by the evidence.