It could be possible that the one that you wanted to watch was not downloaded to your device yet. And since downloading video on cellular data isn't supported yet you got the playback issue. While the other movies were already downloaded to your device before so that's why you're still able to watch it. Since iOS manage the downloaded cache automatically, that Logan movie could be removed from the cache since you said that you're watched that movie about a week ago.
So try to play the movie on a Wi-Fi network, see if it could solve your problem.
You can read the If you have playback issues section from this link for more information:
Have a movie that won't stream to watch.
