Resolved - Some Icon Links in Outlook on the Web Not Working
Microsoft posted a Service Status alert on May 10th that some icon links in Outlook on the web for mail, calendar, To Do, and other services aren't working. They have identified a recent configuration change that is affecting the Outlook on the web UI and are developing a targeted fix to repair the issue. For the most current status please see: https://portal.office.com/servicestatus
As of May 14th there may still be issues, as a workaround please use navigation icons in the App Launcher in the upper left portion of Outlook on the web, or use the Outlook program/app installed on your computer or mobile device.
Update: Microsoft applied a code fix on Saturday May 15th that resolved the icon issue for most, though some users may continue to experience navigation issues via the icon links when attempting to navigate from the "People" module. Another targeted code fix set to be completed on Tuesday, May 18th is expected to repair this functionality.
Resolved: Microsoft confirmed that the targeted code fix was completed and the issue has been resolved.