This issue has been reported in organizations with Microsoft Exchange, Outlook (2010, 2013 or 2016), Apple i Phones/i Pads, Active Sync devices, Apple Macs running Outlook 2011 or 2016, and RIM Blackberries.
For more information see: Exchange Outlook Calendaring Problems.
Note: If you want copies of meeting requests and responses that you receive to be sent to a delegate, ensure that the delegate is assigned Editor (can read, create, and modify items) permission to your Calendar folder, and then select the Delegate receives copies of meeting-related messages sent to me check box.
If you have assigned permissions to a delegate so that he or she can access your Outlook folders, you can hide personal information in appointments, meetings, tasks, and contacts.
The delegate can then move or copy the items from his or her own Sent Items folder to the manager's Sent Items folder.For example, you might have an assistant that you want to create and respond to meeting requests for you.Some assistants might also monitor a manager's Inbox and send email on behalf his or her behalf.Folder sharing lets other people access one or more folders.However, it does not include permissions for them to act on your behalf.