@lbenioff 

The issue appears to be due to negative inventory.  Since you can't sell what you don't have, QB uses the average cost of the last item sold for the oversold items.  But, that's just an estimate because you haven't entered the cost for those items yet.  When you bring in the oversold items on a bill, QB makes an adjustment to determine the correct COGS based on the difference between the estimated COGS at the time the invoice oversold the items and the actual cost entered on the bill.  Those adjustments are what you're seeing.