There may be times when you need to resync invoices and receipts to QuickBooks. If these have already been synced, their flag is set to Transferred. They must set to Not Transferred or Kennel Connection will not try to sync them again.
Note: You must also delete these items from your QuickBooks file before you sync again.
If it's only a few invoices/receipts, click on Accounting, Invoices. (These same directions apply to Receipts).
Find the invoice and double click on Transferred.

Click Yes on the message about resetting the QB ID.

If it is all invoices for a date or date range, click on Accounting, QuickBooks DirectSync.
Make sure NO options are checked, set the date range and double click on Ready. Click Yes to the prompt.

For receipts, check ONLY Vendors, set the date range and double click on Ready. Click Yes to the prompt.
Once the flag has been set back to Not Transferred, you can sync again to QuickBooks.