As well as the automatic sync with Xero Ledger, a manual sync can be run when required to synchronise Invoices and Credit Notes. Running a manual sync will import new invoices created in Xero Ledger and will not update already synchronised invoices.
Navigate to Automations - Apps - Practice Ledger.
Click the Cog icon to open the settings.
Invoices that have not yet been created in FYI since the previous sync date will be synchronised, however, to sync invoices from a historical date, click Edit, and change the Migration Date to a past date.