Hi Timsiggs,
Depending on the outcome you are looking for.
You may be able to filter the "Sales by product/service detail" report, by clicking Customize, and filtering and selecting "A/R Paid" and selecting the option for "Unpaid".
I get a successful outcome,i then click into the invoices as required. I can filter it down further by selecting a specific, or a selection of products/services.
Thanks,