After extensive troubleshooting with Jacob (Airtable customer service rep) through the support channel, it was discovered that the bug only occurred when the password-protected, shared Form view was accessed via a link out from my ruby on rails web application.
The links are embedded in standard HTML, so it’s not clear what is causing them to act the way they do when clicked from within the application. If you are experiencing a similar issue, I will post the resolution here when I hear back from the Airtable team who are working on this.