When a subtask is still incomplete, but its parent task is marked as complete, the visual display of the remaining subtask is misleading.
In this situation, on the default task list view (which defaults to 'all active'), Wrike displays the subtask as if it has no parent task at all. This is misleading because it does have a parent task, and can lead to a lot of confusion regarding, e.g., the inability to remove the task from a folder or move it to another folder (because its parent task is still in the folder, even though you don't see it in the list).
I would suggest still showing the finished parent task, even though the filter is set to 'all active', when it still has an active subtask. Perhaps show it as auto-expanded and grayed out or somehow otherwise distinguished.