Our accounting connectors do not sync updates to invoices made in ServiceBox to accounting.
This can be frustrating, however the reason we don't do updates is that once the invoice has been transferred to accounting, any sorts of changes could take place in accounting that ServiceBox is not aware of. Including the advancing of the accounting session date in Sage, the closing of a period in QuickBooks, manual addition of items in the invoice in accounting by a book keeper, corrections to taxes charged, setting class codes or other fields on an invoice, etc. This can cause two issues if we did sync updates.
One is that we may end up overwriting changes made in QuickBooks Online without realizing we are doing so. This can cause discrepancies in the books and require book keepers to go back and re-fix changes to the invoices.
The other is that certain business rules in QuickBooks Online kick in that prevent changing an invoice. One example is the period could be closed in settings which prevents editing of the invoice. This would cause an error in the accounting connector that would make it very difficult for the user to find and fix.
We generally take the philosophy that your accounting software is your source of your company's financials, not ServiceBox. This is because there is likely more going on in your financials then the activity in your books. Certain activities such as purchasing, payroll, reporting, etc. happen outside of ServiceBox. We see the transfer of invoices into ServiceBox as being a convenience step to avoid having someone manually enter the invoice into accounting to include it in the company's financials.
We do have it in our development backlog to investigate whether or not there is a way to safely update invoices after edits are made in ServiceBox or report on the reason why we were unable to do so but for now we have erred on the side of caution to not mess up people's accounting books.
There are currently two work arounds if you need the two systems to be. If you need to change an invoice in ServiceBox after it has been exported to accounting, manually make the change in both places to keep in sync. Alternatively you can delete the invoice out of accounting, unlink it in ServiceBox and re-run your sync to re-import it.