I had a lot of trouble jellyfin and anime until I started putting things into season folders, even if they only had one season. So if I had Ano Hana I’d put the episodes in a folder like this

Media Disk/Anime/Ano Hana/Season 1/episodes_here

If it’s a movie, then it goes into a folder with other movies.

Media Disk/Anime Movies/movies_here

Once I started doing that, Jellyfin automatically recognized most Anime.