You may experience this Invoice sync error if your invoices have old invoice dates or the accounting books are closed in Netsuite to update the dates, and you have enabled Allow Non-G/L changes permission for the respective period. To resolve this error follow the below steps.
This can be done by navigating to Permission->Setup->Change the Permission of the Role assigned to Chargebee->
Choose Allow Non-G/L Changes here and hit Add.
This shall solve this error.