User is unable to bring some invoices to CORE from QuickBooks Desktop. The user then created new invoices in CORE and deleted the old ones in QuickBooks Desktop. Now, user needs to send the newly created invoices back to QuickBooks Desktop, but they aren't syncing.
This seems like a data mapping issue. At this point, you can reach out to the Support Team for them to take a closer look at your data. There are also a few recommendations for such data sync. Start using the Approval filter in the Sync Settings of the CORE-QuickBooks Integration utility when sending invoices to QuickBooks Desktop. The invoices should be approved after they are sent out to the client. You can use the approval to control when the invoices are sent over to QuickBooks Desktop. This should reduce the margin of error. If the invoices are not transferring, check Smart Match. If you see an entry for the invoice in the Mapped section, delete the entry and try transferring again. Check CORE Help Center for details.