iTunes Extras not showing up in my Library for older purchases, despite being available on the iTunes store.

I have had my iTunes account since around 2009, and I have been buying movies and redeeming digital copies from eligible Blu-Ray discs since that time. I have noticed that almost all of my movies from 2014 and earlier are missing the iTunes Extras. I have checked the iTunes store listings for these moves, and most of them have iTunes Extras listed, so I am assuming they were added after my purchase.

I was under the impression that iTunes Extras that were added to after the fact would be retroactively added to the purchase. I have a bunch of movies from that time that that have since been updated to 4K, but still no iTunes Extras.

Here is an example (with screenshots):

1) I purchased the film Rise of the Planet of the Apes in 2013.

2) The iTunes listing shows that it comes with iTunes Extras. (Note that iTunes says I have purchased this exact version)

3) My Library does not show any iTunes Extra button. (As you can see it's been updated from HD to 4K in the years since I originally purchased it)

I have checked my library on my Macbook, iPhone, iPad, and Apple TV.

If anyone can help me out with this I would really appreciate it. I have spent hours on the phone with apple support, but no one at their call centres seems to understand what I am asking about.