I am using Xporter 3 to generate documents from JIRA issues. The MS Word template uses styles and references to styles in the page header (e.g. to display the current chapter). This does not work with Xporter as neither PDF nor Word output. Having a look at the Word output shows, that all styles have a _0 added to the name i.e. style Normal becomes Normal_0, Heading 1 becomes Heading 1_0, etc. That explains why references to Heading 1 do not work. I saw the problem with version 2.9.x and with the current version as well.
I can reproduce it using your samples e.g. SampleReleaseNotes.docx. It has Normal, List Paragraph and Heading 2 styles, after export as DOCX Word shows them as Normal_0, Heading 2_0, List Paragraph_0.