The Secure Sync was disabled due to an error. Please activate the 'Secure Sync' in the settings of your app again and overwrite the local data.

If this does not work, the Secure Sync has to be reseted:

'Settings'> 'Reset Secure Sync'> 'Delete Cloud Data: YES'

Then you can re-enable the Secure Sync on one of your devices and transfer the data from that device to the other device.