That table is trying to pull in the Food_Price_substitute field from your Menu-1 table. There are 2 "fish" records in that table that are identical except for Food_Price_substitute, so the chart does not know which price to use.
When this happens, QlikView inserts a null as it doesn't have the context necessary to complete the chart. You have nulls and zero values suppressed on this chart object (on the Presentation tab), so these rows are left out.
These records need to be unique in some way. If you were calculating this manually, how would you know what price to use for fish? I would recommend giving each of these fish items a different item_id since they have different prices and then using item_id when mapping.