The incomplete warning isn't resolving subtasks, checklists, or assigned comments.
1 - A Parent Task with unresolved items is closed
2 - Incomplete warning appears
3 - Click "Resolve all Items"
4 - The Parent Task and the previously unresolved Subtasks are closed
What's Happening:
Steps 1-3 are the same
4 - Parent Task is closed, however, items stay unresolved