Line Items in Xero should be populate with default values of Item Inventory
When a line item is added to Xero invoice - it currently do not created with default values. It doesn't make sense to not default to Item Inventory defined in Xero.
If this is a breaking change and break for other customer then a new field which will let us populate line items using default values.
If not, we will need to sync Item inventory in our end before creating any invoices via API.