A Nested BOM shows cost and substructure only to a single level, otherwise wont show anything if the deeper nested BOMs are draft as as well.
if this is correct
it would be very useful to improve the Update Cost button to fetch the cost of the entire Draft BOM structure, even when some of the deeper BOMs are also Draft.
if this is not correct
what should i do to get the cost of the entire Draft Nested BOM
That is correct, when BOM is submitted, it fetches correctly down to the Raw Material but, after been submitted, the BOM gets frozen for ever, it make sense, but it will be very useful that in Draft or creating a non commissioned BOM have the same behavior as a submitted BOM.