I'm happy it's resolved. But it really stinks that adding it to the home page causes that. Apple assumes you want to view it like a regular app instead of a browser page, and removes browser controls from the screen.
There's supposed to be a way to prevent it from doing that, and I tried it here (special tag in the page HTML, still in place). But I'm not 100% sure it worked. The browser testing suite I use only allows access to the browser itself, so I couldn't pin anything to the home page to test. Now that you know how to resolve it, maybe trying pinning it again and see if the problem is gone? Or not, either way, just happy it's working for you now --- I have a response that works which I can give to anyone else who might run into it in the future.
Hopefully, at some point Apple expands what control sites can do so far as pinning and browser behavior.