Our group has found three causes for summary tasks being out of sync with their detailed tasks. 1) The summary task itself is set to manually scheduled. When manually scheduled, the summary task will not automatically update to reflect the detailed tasks below it. 2) The Schedule Option: Updating Task Status Updates Resource Status is not checked. When not checked, the task and resource assignment information can be out of sync…which could then cause the summary task to not reflect correct information. 3) The summary task itself has predecessor/successor relationships. When a predecessor/successor relationship is assigned to a summary task directly, it can impact when the summary task itself can start/finish…which could be different than the detailed tasks below it.