Thanks for providing me with that link. Through the form, I was able to identify the MailChimp account and take a closer look. In connecting your MailChimp account on my end to a local WordPress install, I was able to successfully connect the list in question, where it provided me with the correct field labe, "E-mail". Here's a screenshot of that: http://screencast.com/t/dZlBQFMQ
This is definitely a bit odd, as I'm not able to replicate the issue in connecting the account on my end. It does sound like something may not be getting updated or re-connected properly, so we'll want to test a few things out.
We would first ask that once more you ensure that you are clicking the "update list" button and receiving a success message at the top of the page (in WP-admin) notifying you that it has been successfully updated.
Also, can you clarify whether any edits were made to the actual plugin code? Is it the most up-to-date version of the plugin? And have you attempted to uninstall and reinstall the plugin (I'm not sure if that's what was meant by reconnecting)?
If all of the above has been done and you are still not able to resolve the issue, would you be able to try creating a new list, updating the email address field in that new list and seeing if those changes are apparent in your WordPress install, for that new MailChimp list?