I purchased Pacific Rim in 4K from the Roku VUDU store. For some reason on my LG C1 with a Roku 4800, the captions that should render at the bottom of the screen are not appearing on screen, but captions that are especially tall on the bottom, or render at the top of the screen, are visible.
I am not experiencing this issue in 1080p playback on an older Roku Stick.
The issue is probably something to do with your newer device’s caption settings.
I’m into videotapes and old electronics stuff, including extenders, converters and analog 4:3 TV sets (which are obsolete these days), and Miss Bianca is my favorite character in Disney’s The Rescuers (1977) and its sequel, The Rescuers Down Under (1990). I am not a Roku employee, only a user like you. ~ Jordan