It would be nice if you report a bug on Gitlab and share the URL. Only then can I look at it. Did you check if it might be a "Same-Origin-Policy" issue? If so, it isn't possible to exchange a framework (e.g. Modernizr) because the webserver forbids to load a framework from another source. (https://gitlab.com/nobody42/localcdn/-/wikis/faq/Broken-JavaScript-or-CSS-on-some-websites)