Schoology has announced changes to their embedded Document viewer. Their announcement is below.
On December 29th, we are releasing our new Document Viewer, which provides an enhanced viewing experience for all documents on the web platform. Additionally, educators will have an improved grading experience for assignment submissions on both the web and in the native iOS and Android apps.
Please note that assignments that were annotated using the previous Document Viewer will continue to display the previous experience.
Visit our help center or watch our video for more information.
Sincerely, The Schoology Team