Can't reproduce 4K content on Apple TV 4K

[tiberio13]

Server Version#: 1.18.8.2527
Player Version#: idk but the app is always up to date

I have a Plex server running on my WD My Cloud EX2 Ultra, it works perfectly and I stream to Apple TVs, Iphone, IPad, Mac and Windows machines just fine, not only localy but remotly as well.
The majority of my content is 1080p MKV files, but recently I added my first 4K movie, is a MKV file as well and when I try to watch it on my Apple TV 4K it doesen’t work, it tries to convert it to 1080p so I change to run it originaly, it loads and nothing happens, but if I watch on anything else, my computer over ethernet and my iphone and ipad over WiFi both of them run normally, and my Apple TV, wich is wired, can’t reproduce.
I don’t know why plex is trying to convert the file to 1080p when clearly my NAS can’t do this, and the Apple TV is strong enough to play the file, what should I do? Anyone had a similar problem?
Any tip helps thank you!

[darcilicious]

During playback, in a web browser, visit https://app.plex.tv/app and navigate to the Now Playing section of the server Dashboard, take a screenshot and post it here.

[tiberio13]

This is when I just hit play and try to watch it:

And this is when I try to change the settings to “play at original quality”, for wich it immediately close and say it can’t play the media right now, try again later:

[darcilicious]

Are you using the enhanced player? It’s in the Plex app settings.

Also, is playback better without subtitles?