We cannot directly refer to line field values from the sublist in a record inside a workflow action criteria. Recently, I had to create a workflow to hide the ‘Authorize Return’ for a user if the related invoice is having an item with a specific custom field value(‘Product type’ is ‘Premium appliance’). This custom field was not directly accessible. So, I created a workflow deployed to the ‘Invoice'(Transaction: Invoice) with a sublist action group for items. Under this action group, I was able to refer to the custom field as ‘Line: Item: Product Type’. So, I stored the result of this comparison in a workflow field and used it with the other necessary criteria to hide the button.
