Problem: AppleTV 4K may refuse to display a 4K video in its library listings, or claim the movie file can not be found.
Process: I have 2 4K videos, a THX one I downloaded from Youtube and the opening scene from The Dark Knight, in my home videos library. These files have no metadata – this is important.
I put Tenet into 4K after watching both 4K test videos fine on my AppleTV, streaming from iMac 2014 running Mojave.
Subler, the app I use for editing video metadata, did not put “HD Video: 4K” in the file’s metadata so I did.
AppleTV displayed the Tenet cover art on the main menu screen but gave me the error, “The movie could not be found in your library”.
I double-checked the presence of the file and played it on the iMac, no problems.
I checked the test videos and saw they had no metadata. I put the “HD Video: 4K” into one and saw immediately as the AppleTV removed the file from its library listing. I removed the tag and refreshed iTunes and the AppleTV did not put the file back.
Solution: So I removed Tenet from iTunes, edited the file to remove the “HD Video: 4K” tag, and reinserted it into the library.
AppleTV displays the item in the library and streams it without an issue.
If your AppleTV 4K refuses to display or play 4K videos, it may simply be because of the “HD Video: 4K” metadata tag.
You’ll need Subler or a program like it to edit video metadata.
Edit: I don’t know why people are downvoting this. I’ve been all over Apple forums this morning and searching Google and I’m not the only person who had this exact same issue.
I thought it might be nice to offer a solution.
Additional for TV.App users
I just did a little further testing on my newer MBA running Big Sur.
Just as with the iMac, when a test 4K video had the “HD Video: 4K” metadata tag, AppleTV would refuse to display the file in its library list. There was the Home Videos category, but it was empty. I removed the file from the library on my MBA, edited out the tag, put the video back in, and AppleTV displayed it once again.
Caution: I noticed on TV.app there is no option to Delete from Library but leave the file. You’ll have to copy the file out of your library’s storage in order to edit the metadata before you Delete from Library.