I have downloaded the Gateway theme, and I am exploring it to figure out how Grav works. I have read the manual. The site works fine. One question, though. Looking at 01.home, which is a modular page, it wants to pull in (and does pull in) _showcase, _highlights, _callout, _bottom, and _contact. According to the manual, these should be subdirectories of 01.home, or alternatively of 01.home/_whatwedo. However, I do not see them. Where are they? Where is Grav getting that content? It looks like 01.home is somehow displaying blog posts from 02.blog. Very strange.
It appears that the home page is displaying all the featured blog posts for some reason, after chasing through the css.
The Gateway skeleton has this set of pages: https://github.com/getgrav/grav-skeleton-gateway-site/tree/develop/pages apparently the home modular.md header content is copied from another theme, and has that ordering set up, but those module childs do not exist.
But, that field is just used for ordering.
If now you see the blog posts, you might have switched the home page to /blog in the configuration?
The blog posts are showing up on the home page because featured is set to true on three particular blog posts in the frontmatter, and the featured pages are looped over in some twig file.