Hi Critters222,

Thanks for joining the thread! Let me walk you through on how to find an invoice linked to a billable expense.

1. Open the bill and take note of the selected Customer/Project, date and amount.
2. Go to Customers tab and click on the customer name.
3. On the Transaction List, click on the invoice. 
4. On the upper right corner, click on 1 linked Billexp Charge hyperlink. 
5. Click Billable expense and then Bill hyperlink.

Also, you may check on this article for your reference: Delete customer with unbilled charges.

Message us back if you have any other questions. Have a nice day!