Year / Decade not showing properly

[Lakorus]

All files are MP3.

Here the other requested settings:
aliasTags: All Artists: Artist, Lyrics:Comment, Comment:Nil, OriginalDate:Date
indexTags: All Artists:Interpret, Contentgroup:Allgemeines Genre, Genre, Language:Sprache,-Jahrzehnt, -Date:Jahr, Remixer=Claudias Musik: Für Claudia,Cover-Versionen,Copyright:Mix-CD,-Datemodified:Neue Musik,Encodedby=Komplettes Album:Komplette Alben
itemTags: Comment,TitleSort, ArtistSort, AlbumSort, Album,Originalartist
tagOptions: Artist.ignore.sort={The}, Date.yearOnly.index, Jahrzehnt.decade.index
tagValue: Jahrzehnt.default={Date}, Title.value.sort={TitleSort},Artist.value.sort={ArtistSort}, Album.value.sort={AlbumSort}

As you can see, I used some tags for different purposes. The value "Encodedby" is of no use for me, so I used the tag for noting where the song is part of a complete album.