According to 9to5Mac, the bug has been popping up on all platforms that use the Apple TV app, whether it’s tvOS, other smart TVs, or external streaming devices like Chromecast or Roku. There doesn’t seem to be a clear pattern to the bug either, as it’s not affecting all users or media with any consistency.
Apple
9to5Mac theorizes that this could be a digital rights management (DRM) error that's blocking audio as a copyright protection measure, despite the media being properly paid for.