Ingredient and product item are same in batch

Hello Team,

       In chemical industry, production user follow the process of item rework i.e reprocessing of item.For this they create a batch, item ingredient input qty and product output qty will be same and product is declared.

       Since the item ingredient input and product output are same, cost calculated for this batch is showing as zero and calculated cost is going into variance.Please help what steps need to be done in order to correct this,

       I have attached screenshots for reference.Kindly let me know in case more clarity.