1) Check to see if all the calendar events are assigned to an appropriate time zone.

2) Determine if the invitees have the correct time zone settings configured in their local calendar application.

3) Confirm that the time zone is set correctly in the Microsoft calendar application.

4) If needed, request the invitees to refresh their accounts or reset their calendars.

5) Create a new calendar event and check to see if it is viewable in the correct time zone for the invitees.