Class type in material BOM

Hello,

I nee to insert a new material into a sub-BOM of an exploded BOM. A material class is important to insert under the precise sub-BOM.

I would use a class type to find where to insert the new material but when I get an exploaded BOM with CS_BOM_EXPL_MAT_V2, the fields CLASS and CLART for the sub-items are empty.

How else could I get a BOM with class information?