Article Index links open articles in shaper_helix3 instead of my Article Detail page

I want to create a template for Joomla articles using SP Page Builder. I followed these guides:

• Creating an Article Index Page
• Creating a Dynamic Article Details Page

On the Article Index Page, I created a link to the Article Detail Page. However, when I click the button to view the full article, the content displays using the shaper_helix3 style instead of my custom Article Detail Page.

I expected the full article to use the dynamic Article Detail Page I created. Have I missed a step in setting up or linking these pages?

My existing forum question is still unresolved and has had no support response for over two weeks: https://www.joomshaper.com/forum/question/46609