We’ve run into two items that may be causing your scenario. 1) The Summary Task is a manually scheduled task. When it is configured this way, the automatic roll up / summarization of the sub-tasks does not occur. Change the summary task to auto scheduled. 2) There’s a scheduling option (File>Options>Schedule) “Updating task status updates resource status” that should be checked. if you hover over the information icon next to this option, you’ll see that it impacts calculations of % complete.