The green tagger button is missing for every release for the Korean music group AOA. I can drag the correct release from the website to MusicBrainz Picard and MusicBrainz Picard can find the correct release for AOA tracks using Lookup – it is only the green tagger button that is missing.
Every other page I've visited, before and after, is fine (i.e. the green tagger button appears at every level: artist, release group, release, track).
Link to main AOA page: https://musicbrainz.org/artist/23492596-1fa6-45b1-8de6-eed4a829483b