Why did my task vanish from the screen after I edited it?

The Kitty Todo app and homescreen widget order your task list under the section headers Overdue, Today, Tomorrow, Next 7 days, Future, and Completed, by due date, priority, and description, so if you changed one or more of these values when you edited your task, it may move to a different section and/or position in the list.

To view your updated task in the list, scroll until you get to the task’s due date, and first you will see the Big cat priority tasks with that due date, sorted alphabetically by description, and then the Small cat priority tasks with that due date, sorted alphabetically by description.