Sometimes you may need to reset your Xero connection with Astalty - this could be due to your Xero integration being disconnected for various reasons.
The first step to resetting your connection is to disconnect your Xero account if it's still connected. You can learn how to do this here.
Once you have disconnected your account, you will need to connect Xero again and you can follow the steps to do that outlined here.
If you have Invoice Batches that have failed to sync to Xero due to an invalid connection, you will then be able to go back into that batch and click "Sync with Xero" to re-sync it using the refresh connection. For more information on this process click here