Unable to Make IBAN Field Mandatory Based on Country or Foreign Payment Flag

Problem Summary:
Client requires the IBAN field to be made mandatory on the Supplier Site Assignment > Payments tab, based on specific conditions. Attempts to achieve this using sandbox page personalization and EL expressions have not yielded expected results.

Details:

We attempted to make the IBAN field (International Bank Account Number) required using the below two logic conditions:

Option 1: Based on Country (Territory Short Name)
Objective: Make IBAN required if country is NOT Australia or New Zealand, as those countries don’t use IBANs.

Expression used:

#{bindings.TerritoryShortName.inputValue != 'Australia' and bindings.TerritoryShortName.inputValue != 'New Zealand'}

Result: This did not make the IBAN field required as expected.