Within the Authy iOS app one or more accounts can be “corrupted” and you will be presented with the following message text with an option to restore:

The token is corrupted. Please tap the button to ensure your Authy account is restored and all your tokens work correctly.

This might happen because:

• An error during decryption from a backup, which causes the local decryption to be invalid while the backup is still fine.
• A device specific issue.

To solve this, click the Restore button or reinstall the app. If the issue persists, contact Authy Support for further assistance.