yeah, I know what you mean. Our expected output based on the given data should be both IRN and IWS. But when we're intersecting the results of two queries,there are no common item_ids between these two, this part of the query is returning nothing,as a result, only IWS is being returned. You can have a try in your terminal. I think this issue with only getting IWS is likely due to the logic of EXCEPT and INTERSECT filtering out more than necessary.