Valuated Project Stock is posted to the Balance Sheet G/L account as Inventory. Balance sheet accounts do not usually have Cost Elements. I say usually, as most things in SAP there are exceptions.
You can create Cost Elements for Balance Sheet accounts in special circumstances. One of them are Inventory accounts. You need a Cost element with Special Type 90. In one system you have it and the other system you do not have it. The CO document is a statistical posting for Valuated Project Stock.
