The reason the chess file is transcoding is because the server is reading it as a mpegts which currently does not support HEVC on the Xbox One: INFO - [Plex for Xbox One] [MDE] Starting analysis of 4k (mpegts, hevc, 153, main 10)
The reason that it transcodes to 1080p H264 is because HEVC is not supported in the HLS transport stream and there is currently a bug with the H264 decoder with media over 1080p so anything in H264 has to be transcoded down to 1080p
I can’t say for sure what is causing the transcoder to fail, but this is the error message: Jul 12, 2017 00:43:56.480 [0x70000b3fc000] ERROR - [Transcoder] [stream_segment,ssegment @ 0x7fe880024200] sample rate not set Jul 12, 2017 00:43:56.484 [0x70000ad55000] ERROR - [Transcoder] Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument Jul 12, 2017 00:43:56.486 [0x70000b585000] ERROR - [Transcoder] Error initializing output stream 0:0 --
Typically when I have seen this happen it is caused by the server not correctly analyzing the file when reading the properties of the file. Since this is a sample file what I would try is:
Re analyze the file within plex and see if that gets the properties to populate correctly.
(if you have the bandwidth) is to re-download the file and see if it might have been a corrupted file.
If the file truly is a mpegts, try remuxing it to a mp4 through ffmpeg, or an mkv with mkvmerge or similar tools.
I downloaded the sample file myself and it shows in media info for me as a mp4 and not a mpegts. I didnt try playing it as I wasn’t able to get to my Xbox One to test it out.
I believe that is why the server is having issues. The file has an mp4 extension, but shouldn’t since its a mpegts. As far as I know that is what the line in mediainfo is telling you with the filextension_invalid section. Overall, I would say the server is rightly transcoding it because it is a mpegts, but that whoever created the sample file misnamed the extension.