iOS 8.1.2 and Outlook 2010 Calendar Sync Issue Corporate environment. 
Outlook 2010 running on Windows 7 32bit.
iOS 8.1.2 running on iPhone 6.

Scenario:

User 1 sets up a meeting, using Outlook 2010, and sends the invite to User 2. User 2 gets the meeting notification in Outlook 2010 but not on the iPhone. 

Also, if User 2 creates a new meeting on their iPhone the meeting never shows on User 2's Outlook 2010 calendar.

The iPhone is using Mobile Iron to handle the Exchange account.
Settings > General > Mail, Contacts, And Calendars > Scroll to the bottom where it says Default Calendar and make sure the "On This iPhone" option isn't checked. If it is then you need to select the appropriate calendar for this be it your FIRM or Corporate Calendar. An option your IT Administrator or if your FIRM or Corporation requires to have an app for would have been preloaded and installed already on the iPhone or iOS Configuration