My iPhone Reminders are synchronized with an Exchange 2010 account. Reminders sync correctly except for one thing - when completing a task via the iPhone UI, the task on the Exchange server is marked as 100% complete (with Status == Completed), but the reminder is not cleared. This causes reminders to pop up for completed tasks in Outlook, OWA, etc.
When a reminder is completed via Outlook or OWA, the reminder is correctly disabled. Also, un-completing and re-completing the same task in Outlook correctly clears the reminder.
I have tried this on two separate Exchange 2010 servers, and with two different iPhones (4S running IOS6 but the problem existed with IOS5.x also).
How can I get the Reminders app to clear the reminder from the Exchange task when marking it complete via the iPhone?