Please note that your newly received and activated Mastercard card/-s is/are associated to your IE IBAN.
Note that even if your total balance was sufficient, if the balance in the corresponding to the card IBAN was less than the transaction you are trying to process, the payment cannot go through.
As your account has been successfully migrated, your only active IBAN/-s is/are the new IE ones, therefore, you should not encounter similar difficulties.