Troubleshooting: my Office 365 shared calendars don't appear in Front Calendar
After connecting your Office 365 calendar to Front Calendar, you may notice that some of the calendars you normally see in Outlook calendar are not available in Front. This has to do with a change that Microsoft made with the way users share their calendars. If the calendars were shared prior to the change, they are not available by default to services like Front Calendar, and must be re-shared.
For each calendar that is shared in Office 365 but not available in Front Calendar, use the following steps to make it accessible in Front.
These steps should all be taken in Outlook on the web, not desktop.
In Outlook calendar on web, remove the calendar that you were previously shared on. Instructions for doing so can be found here.
Have the owner of the calendar re-share the calendar with you. Instructions for how to do so can be found here.
In Outlook on web, you should receive an email notification that you are being shared on a calendar. Click the link to accept the shared calendar.
Refresh Front, and check your calendars to confirm that the shared calendar is available.