Hi folks - I am new to MS project and am struggling with the metadata on summary tasks. You can see in this image I have an 'Initiate Project' summary task which consists of several sub-tasks. When I mark one of the subtasks complete, Project marks the summary task complete too. Even though all of the other subtasks are still incomplete. The summary task shouldn't reflect complete until all of the corresponding subtasks are complete.
This is because your tasks are manually scheduled in your example and those tasks do not have any duration. Either add duration to the manually scheduled tasks or switch to auto scheduled tasks like in the example below: