Why do flac files get transcoded to mp3 when played on the nVidia Shield TV?

android-tv
fire-tv

#1

Running PMS 1.13.2.5154 with Plex Pass. When I play back a flac file using the latest Plex app on nVidia Shield TV, the server shows that it's transcoding the flac file to mp3. If I Chromecast from my phone to the nVidia Shield TV, it Direct-Play's. Is this expected? Does that mean that the Plex app for the nVidia Shield TV can't handle flac files even though the box itself seems to?