I see no recent updates for this show https://www.themoviedb.org/tv/112442-trash-truck/changes?filter_key=key&filter=images. Are you sure you did upload them correctly ?
According to Once Upon a Time in the West metadata - #4 by dane22 plex needed to remove some artwork due to legal requirements. I would (always) recommend using local asset artwork for your media → https://support.plex.tv/articles/200220677-local-media-assets-movies. That way you can fully control the artwork and you are not reliant on plex for it.
