How to deal that data in Mi cloud service that cannot be synced back to phone or tablet?

Solutions:
1. Confirm that the login account of the user on the web side and the mobile side is the same account.
2. Try to change the network environment. It is suggested that users try to synchronize the cloud data to the mobile phone in different network environments.
3. Delete the MI account in the phone or tablet. When deleting the account, the system will prompt whether to delete the contacts and notes on the phone. Select "Delete from mobile phone" and re-bind Mi account to synchronize the data back to the phone.