Using the default templates my PDF does not retain my DITA map hierarchy

I am building DITA documents in FrameMaker 2019. The hierarchy in the DITA map is not being reflected in the PDF output I generate. For example, in one small document I'm developing I have the following hierarchy of topics:

- What is DITA

     - Why Choose DITA

     - Focus on Best Practices

         - Minimalism

         - Structured Writing

         - Topic-Based Writing

         - Content Re-Use

     - Core Structural Elements and Attributes

           - The DITA Specification

               - DITA Maps

                    - DITA Map Definition

                    - Book Map Definition

               - Concept Topic Definition

               - Reference Topic Definition

and so on

But the ToC in the PDF looks like this:

What is DITA

Why Choose DITA

Focus on Best Practices

     Minimalism

     Structured Writing

     Topic-Based Writing

     Topic-Based Writing and Minimalism

     Topic-Based and Structured Writing

     Topic-Based Writing and DITA

     Content Re-Use

     Identifying Shared Content Within a Suite of Documents

     Identifying Shared Content Within a Single Document

     Writing Sharable Content

Core Structural Elements and Attributes

The DITA Specification

     DITA Maps

DITA Map Definition

and so on.

Within the PDF, the chapter and section numbering does not match the ToC numbering.

The first two topics appear correctly, but then every topic thereafter is on its own page and the heading styles do not match the ToC headings.

Is this an issue with the default templates that I need to work out with new templates or is there another issue that I'm missing here?

Many thanks,

Wanda