Troubleshooting Outlook Calendar Issues:

1. Check your timespan. Make sure you are viewing the desired date range in the Calendar view.
2. Check your filter. Check if you have applied a filter to the Calendar view.
3. Try disabling the cache. See if your calendar events re-appear when Outlook is not using a cached mode.
4. Check for corrupt Calendar files. They may need to be removed, repaired, or deleted and re-created.
5. Check for incorrect time zone settings, incorrect daylight saving times, or mismatched regional settings. Make sure that the Outlook clients are all synchronized with the Exchange server.