How do I troubleshoot a custom Dunning Letter?

Summary:

I've created custom dunning template in Shared Folders/Custom/Financials/Collections/Correspondence and supported the template with a custom data model saved to Shared Folders/Custom/Financials/Collections/Correspondence/Data Models as specified in documentation How do I make the custom layouts available in the "Correspondence Template" LOV on Create Task in Manage Strategy Tasks in setup and maintenance?

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

Fusion Advanced Collections 23C