Schedule

Two different questions, kept apart. Due is a commitment and is what a schedule means; started is a record of when work began. Only 0 of 0 tasks carry a due date, so the due series is a floor and the start series is the one that shows the shape of the year.

Overdue

Past a due date and still in Backlog, Todo or In Progress.

Nothing overdue.

By due date

No task in this range carries a due date.

Work started, by month

Every task carries a start date, so this is the one complete time series in the registry.