Hello @Ethan_Ye
Reason thats happening is because something is going wrong with the transformation. I believe its because of this line:
"priceListId": {{ $item.priceListId }},
More specifically this $item.priceListId. Unless you changed the input structure the right key name is itemId . And the right line would be.
"priceListId": {{ $item.itemId }},.
Let me know if that works.
Zaid