When you run a P&L report and select ConnectBooks Costs with Fallback or ConnectStock Item Cost, you may see no cost on certain line items. This is expected.
Fallback costs only apply to marketplace transactions. They do not apply to ConnectStock file data, like customer invoices. For those records, we pull the cost only if one is explicitly tied to the transaction. If no cost was attached, the line stays blank rather than substituting a fallback value.
If you want a cost to appear, make sure the transaction itself carries a cost, for example by entering a bill or recording the adjustment with a cost value.