Hello Paul,
I have logged in and checked your gallery page. You have set up your Looper Providers and Looper Consumer incorrectly. Kindly edit the page and make sure that you follow this setup:
1.) The “Gallery” section should be your Looper provider.
2.) The “Gallery > Row 1” should be your Looper Consumer since you will be expecting more post items to display and separating them by row will make it more proper.
3.) If you have watched the video tutorial in setting up the ACF Gallery, (https://www.youtube.com/watch?v=BFJdDM078VI), you will have to set up a nested Looper Provider inside your first provider. In your case, the “Secondary Images” div element will be the Looper Provider.
4.) The Looper provider will be set to “Dynamic Content” and use “{{dc:acf:post_field field="secondary_images"}}” as the dynamic content code.
5.) The “Figure” element will be your Looper Consumer. This will be used to display the gallery images.
6.) And lastly, your image element will have a dynamic content “Looper > Current Item” to display each of the images in your gallery.
Hope this makes sense. Kindly check the secure note as I have created a test page with the steps above for you.