Missing Custom React Components When Launched With Heroku

I’m having some trouble getting a custom streamiit component (built in React) to load when I launch the app to Heroku. Has anyone built a custom component before and been able to successfully launch it into production? Any help would be greatly appreciated! Versions: Streamlit — version 0.70.0 Python — 3.8.2 OS — macOS Big Sur 11.3 Google Chrome — version 90.0.4430.93 The referenced code chunk is:

 # _RELEASE = False
    _RELEASE = True
    if not _RELEASE:
        _component_func = components.declare_component(
            "kanban", url="http://localhost:3001",
        # When we're distributing a production version of the component, we'll
        # replace the `url` param with `path`, and point it to to the component's
        # build directory:

        parent_dir = os.path.dirname(os.path.abspath(__file__))
        build_dir = os.path.join(
            parent_dir, "kanban_list/frontend/build") # changed to point to the build directory
        _component_func = components.declare_component(
            "kanban", path=build_dir)

The code doesn’t provide any error and just doesn’t seem to return any custom component at all.