Customers in SaaS using Braintree are unable to add a billing address or edit credit card details (when they have no billing address defined): when a user clicks on the Edit Credit Card Details link, the form is not rendered. Users who already have a billing address are not affected. The browser's console logs are attached.

This could be due to this change which apparently makes some values in the billing address "required" in order to load /admin/account/braintree_blue/edit.
Since Braintree has no validation on the current billing address in order to load the form, any Account that has no billing address will end up loading current_account.edit_braintree_blue_credit_card_details_url.
Since the form requires a billing address to load, it's impossible for new Accounts to add the billing address for the first time.

A customer confirmed that:
1. This issue affects all of the Developer Accounts (they received multiple complaints from their customers and were able to replicate on a test account)
2. The workaround suggested worked