Hi @allan.crabtree
If you set the posts home page to appear on a static page (Homepage), then WP will change the query run to only find posts, not find the page (Homepage).
This is a limitation with WP, not ACF.
To get around it, you can load the data specifically from the Homepage using a $post_id parameter on all get_field / has_sub_field functions.
You can read about this here:
http://www.advancedcustomfields.com/resources/how-to/how-to-get-values-from-another-page/
Hope that helps.
Thanks
E