Next Generation Supplier Self-Service Registration (Event Listeners Not Working)

Summary:

I’m trying to add an event listener to Call REST and Fire Notification in the Action Chain, but none of the available listeners I’ve tried are working. I initially tried firing a notification just to test the trigger of the event listeners. For context, my goal is to validate the DUNS Number value under the company details through an external REST API. Here are the event listeners I’ve tried just to test the triggers: In Fragments > rs-company-details: - onSaveEvent In register-supplier-start page: - submitActionEventListener Is anybody here encounters the same issue or have done this? Or is there any way to do a validation rule over the "Continue" or "Submit" button in the supplier registration page to achieve this requirement?