Keep in mind the Android TV won’t display those extras on the season level – just in case you were using that to check. Also, Plex Web will only show the tv-show tier extras.
Names/structure of your example look ok. I take it your library is pointing at the parent folder of that show’s folder (Avatar- The Last Airbender (2005))? You refreshed the show’s metadata – not just scan the library for changes?
Ok, I needed to refresh the shows metadata. That information should be in that article since it wasn’t needed to add the inline extra for a single episode. Good to know though, since now I have to check my Specials before I do this for other shows to make sure they haven’t changed. That can cause a mess.