Right now this message isn’t very meaningful. For example, it is displayed if the password is incorrect.
It’s not a matter of “syncing”, but rather “migration”. That is, it is a one-time movement from one backend to the other. There are two backends (V1 and V2) and when you attempt to log in, the app checks whether a V2 account of the provided name exists. If so, it attempts to log in. If there is no V2 account, it checks for a V1 account with the same name. Currently, if the password is incorrect, it says something like “User doesn’t exist”. We’ll clarify this in the app.
So now when you attempt to log in, it will always go straight to the new empty V2 account. There’s a simple solution: WiFi reset the Bond by holding down the pinhole reset button until the LEDs start blinking green (and no longer). Set the Bond up on your WiFi with the V2 app. Your fireplace should still be present (as it is in the Bond’s database), and you still should be able to use all the V1 services (as the Bond would still be associated with your V1 account)