it’s not so incredible when they disappear from your collection, though. It doesn’t happen very often, but when you’ve allegedly ‘purchased’ a movie and it suddenly goes AWOL from your purchases on Apple TV, that’s a major annoyance. Case in point, I ‘purchased’ the very touching movie Lilya 4 Ever some time ago. Now gone from the store. Now gone from my purchased movies.
That's incredibly unusual.
I get the impression that it is human error by an Apple member of staff when this happens as it's so rare for film - happens to the old music videos all of the time though. I happened to me even though the film was available to buy still on the iTunes Store.
Usually the file of the film gets updated and your purchase is assigned to that.
Have you an emergency backup of it?
Also, do get in touch with Apple for a refund or least she free rentals as this is stealing. If you can't stream it to your Apple from Apple once you've purchased it, then that is pure theft. Don't forget the Apple TV is marketed as a streamer. It does not allow you to download that purchase to the Apple TV to keep!
UPDATE: Out of interest, I researched the film of yours. It's from a tiny tiny distributor. Just like my film disappearance, again from a tiny distributor. It's possible that Apple don't have such agreements with these tiny houses compared to the big players?