Hi @Karol, thanks for the feedback.
- If you uncheck 'Due Date', it'll work as you want. Checking it will ignore start date.
- Tasks will be filtered first with 'unstarted' option and then 'Later tasks' will be removed if it's set to be hidden.
Reference)
- Scheduled Smart Lists with start dates
- Later tasks are tasks that's due today but later than current time. Unstarted tasks are tasks with start date which have different start time and due time.
Thanks!