Can't choose external player

I want to use an external player because mkv files can’t be played by Jellyfin android app, but VLC and Kodi android apps can play the same mkv files fine .Jellyfin app don’t let me choose VLC or Kodi, even I have both installed and working, but it say there’s no external video player app installed.

This is happening with Jellyfin android app, on a Firetv sitck and a Xiaomi mi tv.

We have VLC built in as a playback option, and I believe it’s been updated recently too. If you choose that, does it playback inside the app?