The Copyright On "Happy Birthday To You"

It exists, apparently, and yet doesn't:

The song that became "Happy Birthday to You," originally written with different lyrics as "Good Morning to All," was the product of intense creative labor, undertaken with copyright protection in mind. However, it is almost certainly no longer under copyright, due to a lack of evidence about who wrote the words; defective copyright notice; and a failure to file a proper renewal application.

Someone missed out on a fortune.