I am having the same issue.  What I did was updated the standard cost, for example item "A" using IN-L-E.  Then I went to rollup cost for a finished item that consisted of updated standard cost item "A" using BM-G and it is also pulling in incremental costs, which is significantly overstating our inventory value.  I then checked the standard cost on another finished item that uses the same updated standard cost of item "A" and I rolled up the standard cost.  It to was pulling the incremental costs and overstating inventory value.  I don't know if it has something to do with updating standard cost for raw materials then going to rollup the bill of material that would cause incremental cost.  Any help would be appreciated.
 
Thanks,
 
David