Corporate Card Transactions not loaded for employee

We have a case where, previously employee was not assigned to Corporate Card. Those transactions were not loaded into the system as well from Bank's file. Now that the employee added to Corporate Card, the transactions are being imported from the date of assignment. What happens to previous transactions before the card assignment? Bank Says those transactions were already sent but we don't see in the system and they're not errored out as well. We are using MasterCard.