@j.vonstetten 

Run the Inventory Valuation Summary report.  Click on the '0.00' under the CALC. AVG column for the Dragon Blends Fire Massage and Muscle Oil.  That will show you exactly how it's calculating 0.00.  It will show how inventory was increased and at what cost and how it was decreased and at what cost.  Somehow, all inventory on hand for that item has been added to inventory at $0.00/ea.  Post a screenshot of that report.