If the play history, for example problems that your child solved or monsters that he or she collected, has disappeared, please check the following items.
Please make sure you have selected the correct user.
You can create up to 3 users when signing up to one account. Please check the name of the user whether or not you are selecting another user. You can find the current user name on the start screen or the menu screen.
Please make sure you are signed in to your email account.
For sync users, you won't be seen when you sign out your email account. Check if you are signed in at the Parents page, and if not, please sign in with the account that you played.
Please make sure your email account is the same.
If you do not see the user you are signed in as, check that you are signed in to the email account you used to play.
Please make sure it is a sync user.
If you are not using the sync feature, you will not be able to save what you've played when you switch devices. Create a sync user so you can continue to play what you've played on any device.