So.... two phones currently logged in with LastPass and LastPass Authenticator.
Adding an Authenticator code to one of the phones, "Backup completed" shows up, but the other phone does not synchronize with Authenticator backup.
How can I force synchronization? There is a "Backup Now" button, but that button should really be "Synchronize now". The only way I've figured out to synchronize is to delete the application, then restore the entire application. That is a heavy lift.
Authy does not have this problem. Whatever is synchronized with Authy winds up being synchronized with all phones.
Sorry for any confusion with the LastPass Authenticator app, as it is intended to be used mainly on one device. You can use the Backup to LastPass option to back up all of your codes, and then use the Restore from backup option to move those to a different device. Please note that push notifications will be transferred to the device on which you restore your database as they can only be enabled on one mobile device at a time.
As you've noted, Authy does enables you to sync them across multiple devices and may be a more fitting Authenticator app if you are looking for that functionality.
I too am having issues with this. I have two devices that I consider secure enough to keep 2FA data on for some redundancy. Both are connected to lastpass on the same accounts. The phone has the current 2FA tokens while the tablet has them up to a point and isn't getting any new ones. Both devices show that they have backed up successfully. Deleting the app off the tablet and having it restore from the account's backup still gets it only its limited set.
I generate new 2FAs rarely enough that I would be fine if I have to delete the app on one device and restore it to have redundancy. At this point, I am not even sure if I would recover all of my 2FA moving to an upgraded phone (which is the main reason I wanted this app in the first place). Is there something I can do to get a complete recovery of 2FA tokens, even if there is a bit of heavy lifting required? I am not concerned about moving push notifications from device to device, as I don't really use that method.
Are you able to create a backup of the tokens on the original device (In the app, open Settings from the side “hamburger” menu and toggle the “Backup to LastPass” option on) and then restore that backup on to the second device, or are you doing this process and it is not restoring all tokens? Please note you also need the LastPass app and must be signed in to your LastPass account on the device to backup and restore your tokens.