iCloud Sync

You can use iCloud Sync by purchasing a premium service. (Sync data between iPhone, iPad, and Mac)

Check 2 Settings

  1. App's iCloud Settings
  2. Device's iCloud Settings

Please check both App Settings and Device's iCloud Settings on all your iPhone, iPad, and Mac.

1. App's iCloud Settings

  1. Turn on "iCloud Sync" in Settings on all devices.

*Data may not be reflected immediately. If the data is difficult to reflect, please close the app on each device and reopen it.
Now your data will be synced automatically. If it still doesn't sync, please check the following Device iCloud Settings for your device.

2. Device's iCloud Settings

Please read Apple's Support Page.

Check the iCloud Drive settings for all your devices.
From the stock iPhone Settings app..

  1. Go to Settings > [your name].
  2. Tap iCloud.
  3. Turn on iCloud Drive.
  4. Scroll down and then Turn on "To Do List"

If you still have problems, restart the app.

Timing of data synchronization

The data will not always be reflected instantly. If the data is not reflected easily, please close and reopen the app on each device.
The timing of data synchronization in iCloud seems to be done automatically by the OS at the right time. This probably takes into account the battery, communication volume, and various other factors.

Apple System Status

You can see the status of iCloud itself here.