Why do I not see the conversion rate on my supplier contract?

The Fulfillment tab of the supplier contract displays a conversion rate if a ledger is assigned to the business unit of the contract.

If you created the contract without setting up a ledger, then the cost of executing the fulfilment is based on the ledger assigned to the purchasing business unit.

The conversion rate is required only when the ledger assigned to the business unit of the contract is different from that assigned to the purchasing business unit. In this case, the conversion rate calculates the fulfilment cost by converting the currencies of the ledgers.