Strange problem with snippets not loading as expected

I am attempting to develop a bunch of revisions to our ExpressionEngine site. It’s an old site running v2.11.6. For reasons, I have set up a hidden template group on the production site, copied over the templates needed, renamed things and so on to get the development area to work without interfering with the production site.

I have a page template in the development group, which is a copy of the template from production. The footer of the page uses a snippet, as the footer is the same on every page of the site.

This page_end snippet includes two snippets and one global variable. The first snippet loads the content that appears in the page’s footer. The second snippet loads JavaScript the site uses. The global variable loads a little bit of code loading a feature on the site, then loads the tags that close out the page’s HTML.

In production, this works fine. In the development template, it works fine as long as I load the production page_end snippet. When I change the template page to load the development page end snippet — which is just an exact copy of the production page_end snippet at this point with the exception of the snippet name — the two snippets that are called from this snippet do not load. It just displays the snippet names in the curly brackets that is in the page_end snippet. However, the global variable it calls loads fine, just as expected.

I have been beating my head up against this all day, and cannot find any clue as to why this is behaving this way. If I call the production page_end snippet, it works fine. If I call the development page_end snippet, even if its contents are exactly the same as the production snippet, the snippets it calls do not load. I have been unable to make it do anything different.

Any suggestions?