I'm trying to add phone and address fields to the account registration form, as per this SO post.
To override the core functionality, I copied app/design/frontend/base/default/template/customer/form/register.phtml to app/design/frontend/{package}/{theme}/default/template/customer/form/register.phtml, as would be expected.
The problem is that no changes are detected when added to the new template, not even simple changes such as editing field labels. Stranger still, not even changes made to the core template are detected.
I have verified the file paths are correct, including namespace, and made sure file ownership and permissions are correct.
I have cleared the Magento cache many times (all of it), and even tried viewing the page in incognito mode and with other browsers to rule out browser cache. Also, there is no caching at the server level.
Am I missing something? I've successfully overridden core template files numerous times before, but is there something more that I need to do for the registration form templates?