I can play “The Fog of War: Eleven Lessons from the Life of Robert S. McNamara”, a multi gigabyte Matroska file at 718p resolution, with Plex desktop player for Windows. I can play this video with Plex Web player for Chrome.
SHA256 checksum 7ce980bc0ad5577ebf8b406172def3287b4552856821449d8122fb6f7800606b
But when I try to play the very same video file in the Roku TV app (which generally works okay for a wide variety of content), then the app suddenly stops just a few seconds into the film, jumping to the kind of UI landing view as if the film had ended right there. The video continues to be marked as unplayed. The error situation is silent. No error message of any kind displays to describe the problem.
So this represents at least two bugs. Some kind of error during playback, as well as a failure to propagate the error up and inform the user of an issue.
Using the latest stable release of Plex for Roku.