Some device manufacturers add very aggressive power saving features. This can in some cases interfere with the native Android alarm manager features.
Huawei devices: Android settings -> Battery (power saving mode) -> App Launch -> Untick Tasks -> Tick all 3 options (Auto launch, Secondary launch, Run in background).
Asus devices: config -> battery -> boot manager -> downloaded apps -> activate the "Tasks" app.
Xiaomi devices: Battery settings -> Power -> App battery Saver -> select the "Tasks" app and choose No restrictions (for Background settings), then Allow option for Background location.
Lenovo devices: Setting -> application -> select "Tasks" app -> uncheck Restrict to launch.
Honor devices: Settings -> Advanced Settings -> Battery Manager -> Protected Apps -> there you have to slide the Switch to active "Tasks" app. Its grey (deactivated) by default.
Honor device with Magic UI 2.0.1: Settings -> Battery -> App launch -> and then manually manage "Tasks" app.
Vivo devices: Settings -> More Settings -> Permission Management -> Autostart -> Enable the slider for "Tasks" app.
Samsung devices: Battery settings -> Unmonitored apps -> Add "Tasks" app to the whitelist.
Samsung devices: Battery -> Detail -> Select "Tasks" app and "Don't optimize".
Samsung devices: Phone Settings -> Device Care -> tap the battery icon > press the 3 dots at the top right of the screen -> tap Settings -> tap on Sleeping Apps -> long-press the Tasks icon to remove it from the list
NOTE: Tasks will honour the schedule set. When you receive a notification the date and time will automatically increment to the next occurrence. Recurring tasks will be reset at midnight ready to be completed again.
Tap the parent list header. This will display the task list dialog.
When you delete a task or list a temporary popup will be displayed at the bottom of your screen. This has an undo action.
NOTE: Deleted tasks will be moved into you Deleted Items list accessible from the side menu.
The widget can display any list viewable in Tasks. To change it tap the list icon
The widget can be resized to meet your needs:
Note when the widget is full width, date and times will be fully displayed.
Tasks has a built in backup/restore function available in Tasks settings. This is useful when moving to a new phone. When you tap backup Tasks creates a tasks_backup.json file in your /Download directory.
Open the menu and select "Delete List". Note that if there is only one sub list the main parent list will also be deleted automatically.
If you find swipe to delete is not necessary for your needs it can be disabled in the apps settings.