Not able to find existing bank accounts in Customer Site

Summary:

Business not able to find any of the existing bank accounts under payment Instrument tab for Customer site (Manage Customers).

Content (please ensure you mask any confidential information):

We have three different customer sites for three different customer accounts under the same organization, but they all have the same bank accounts. When we created a new customer account and customer site, we couldn't add an existing bank account that was already tagged in three customer sites.

Please let us know why it is not showing any of the existing bank account.

Version (include the version you are using, if applicable):