Identifying invoices with the Issue
Click the Accounting Tab on the Invoice and then Click General Journal.
General Journal button on a Sales Invoice.
If you have any product items on your invoice, you should see an entry for COGS and Inventory. If you do not, the invoice needs to be fixed. The entries in question are in the screenshot below.
A product item with COGS and Inventory entry in General Journal.
Posting them (click the Post button) will fix the issue, but you may experience an error about insufficient inventory. This is because you subsequently sold the item that was meant to be sold on this invoice.
To remedy, you may:
1.) Create an inventory adjustment to bring the quantity on hand to an amount that will cover the invoice. This must be done on a date before the invoice date.
2.) Create a PO/Item Receipt/Bill to bring in the needed inventory (again before the invoice date).
3.) Decrease the quantity on the invoice.
Once the inventory issue has been resolved, post the invoice and verify the journal entries are present.