Older calendar events from Outlook need to be added to the Centerbase calendar.
1.) Go to System Settings by clicking on the gear in the lower left hand corner and selecting "System Settings".
From here, click on "O365".
2.) Check the box next to the user, then click on the green box that says "Pull Selected".
3.) Click on the dates needed, either today and future, a date range, or all dates. In the second option, you can choose which dates to pull in from. Then, click confirm when the date range is correct.