There is a case when the commercial excess it doesn't appear on the Invoice Reception. Precisely, it doesn't appear when goods are received as raw material.
Let's see a concrete example: You create 3 different products from the same raw material, Absolut Vodka. You're selling those products in different quantity and at different prices.
If you receive Absolut Vodka at 0.7l as a raw material, when the Invoice Reception is generated, the commercial excess it can't be created, because it will have different quantity and different selling price.