4K Upgrade Question

These movies are not showing in 4K even though it says that I have these movies in 4K. I tested this out and movies in 4K looked crisp and sharp while movies "saying" they are 4K but don't seem to be are blurry and SD looking. I think this is an Apple bug that Apple has not fixed. These movies are now in 4k but they are lumped as a whole as 4K movies even though they may no longer be sold in SD. It's a strange bug that has deterred me from buying movies to update my SD movies to 4K because I am weary about purchasing the content "again" and thus wasting money on content the library says I already have. It's interesting because when I purchase the 4K version, often times it says "You already purchased this. Do you want to purchase again?" and I tap BUY. But the content I had was SD quality. It recognizes that I have the content already but not the quality I suppose?

Thank you for your answer. How I was able to find out what was truly 4K and what was not was by using the iTunes Movie app that is built in to the Apple TV device. It tells you what is 4K and what is not. I wish the actual Apple TV app that is built in was fixed to include that information so I don't have to go into another app to check each time, but it is a short workaround that helped me. Hopefully Apple will fix this bug soon, if it is a bug.