That's why I suggested to put the formula in column H, not G. There is a way to allow circular references, but you need the iterations defined. File>Options>Formulas>Enable iterative calculation. However, that won't solve this problem as the total for G11 will always be 0 because G11 just sums everything above it, which the line item totals in your first workbook post would be over-written by the formula I wrote if put in G.
So I think the best bet would be to put the formula in H, or if you want to keep it in G, you need to change the total order value formula to:
and put this formula in G2: