Find the answer to your question
Why is SellingManagerProductDetails.ProductName not returned in the GetSellerTransactions call as documented?
Selling Manager Pro users have the ability to create Products which are essentially listing templates.
Each product has a name associated with it, and this is referred to as the Product Name.
Once a Product is created in the Inventory of a Selling Manager Pro user, items can be listed directly using the Product.
Every sale for an item listed using a Product will be tagged with the Product Name.
As long as the Product exists in the Inventory,