It seems like that some of his songs, such as this one published in 1928, will become public domain in 2024. However, this article claims the song will enter the public domain in 1923.

Then you have this article, claiming:

“The Big Rock Candy Mountain” might not actually be under copyright; it’s complicated. It was recorded and published in 1928 by Harry “Haywire Mac” McClintock, but a prior copyright by another party was filed in 1906. McClintock managed to find proof that he’d been singing it for years before that, asserting that he wrote it in the 1890s. And it’s based on material that goes back centuries. But even if Haywire’s 1928 copyright was valid, it should have entered the Public Domain no later than the end of 1984.

Does this only apply to this song? What about his other works, like this one? Why 1984 when public domain day for works made in 1928 is 2024?

Any explanation to understand this would be greatly appreciated. Thanks!