Tip time: when you start changing something, and it stops working, you can always try the previous version again to look for differences.
- you can inspect the requests sent to the backend (using the browser Network tab, or form the logs or rails log/development.log)
- you can look for the generated HTML on both versions and try to identify missing fields, different actions, etc.
Always make sure that the previous version is working as expected, sometimes we start changing something that is already broken and have no working version to compare. (been there)