Here’s the overall help documentation on this feature (https://netsuite.custhelp.com/app/answers/detail/a_id/30564) I don’t believe it can ‘break’ per se, but it can be prone to GIGO, just like anything else. It’s just sourcing information based on the instruction on the txn line. Since you say there’s more than one option available I assume you’re using non-inventory for resale items? All of the options are dictated by the item record (purchase price, preferred vendor rate, item defined cost) or the actual PO (Last Purchase Price or Purchase Order Rate in the case of a dropship/special order). So whichever you pick, that’s what NS will source to calculate estimated cost, and then do math to calculate profit.