By default the 4K movies/tv series libraries are not present in the base appbox image, the paths to these libraries need to be added by the user.
1. Navigate to https://app.plex.tv/ and click "More".
2.Next, hover over your server name, and click the + icon for "Add library".
3.Select the library type either Movies or TV Shows giving it a name for example “Movies - 4K”, after that click Next.
4.Click on “Browse for media files”.
5.Add the right path for the library that you are adding.
If you are adding the 4K Movies path, the following path is correct
/mnt/4K/Movies-4K
If you are adding the 4K TV path, the following path is correct
/mnt/4K/TV-4K
The example from below is for the 4K movie path
6. Click "Add Library" without modifying anything from the "Advance" tab.
Do the same for the 4K TV Series, the only difference is that at the step 3 you will select “TV Shows”