Two stocking types are usually not copied from BOM to Consumption, by extension the Shop Floor:
1) Phantoms - Parts which are a logical (not physical) grouping. Typically models and options are categorized as Phantoms.
2) Child of Buy / Purchase - Sometimes stocking type will change due to being cheaper to outsource (or insource), so a tree of child parts becomes irrelevant (or relevant). When outsourcing, how the part is built no longer matters for consumption or shop floor