In the last week users have been reporting that PDF docs are not displaying any bookmarks panel on left site of browser. These PDFs are opened from a Sharepoint Online page using EDGE, CHROME or IE11. The bookmarks display if i download the PDF and open it in Acrobat. We don't even see the bookmarks menu icon to the left of the other adobe menu icons.
We're not aware of changes in Sharepoint or the browsers that would cause this to disappear.
Any idea why the bookmarks disappeared and how to make them appear in the browser display again?