I also failed to synchronize recently. I called the official customer service to ask, saying that it was because I used the same account to log in to the global service network and China service network, and gave me the following solution: (I still haven't solved it) Please log in to the following websites with two different browsers for data confirmation. Or switch the authentication domain in the APP login interface according to the attachment and log in to the global server website corresponding to the server account:/At present, third-party software such as Migu and Gudong cannot be used for the global server account. At present, some third-party software, such as strava\Mfp, has not been docked with the China server, and our company is also contacting some third-party application providers. Once it is completed, we will notify the China server users. I also need to explain to you: 1, China server and global server are independent due to the restrictions of national network laws and regulations, and only accounts on the same server can add friends. At present, 10 and 15 have completed all relocation matters, and the relocation has stopped. 2. We don't recommend using the same mailbox to register accounts on two servers repeatedly. This may lead to confusion of account data. Please refer to the following link /zh-CN/account/ to delete the domestic account and send it to Service.cn@garmin.com customer service email or call Garmin official customer service: 4008 19 1899.