Hey @1969rsldai! It sounds like the invoice may either be marked as paid, which you should be able to check by selecting the invoice and choosing the option to Remove Payment (if it appears).
If this isn't the case, is it each line item that is showing a price that is 0? Or does each individual item have a price but the overall invoice has a total of 0? This latter issue can happen if any one of the line items was entered with a negative value, which may have zeroed out the invoice total.