After trying everything and asking in the Forum I dare to call it a Bug:
The playlist related placeholders ( %_playlist_filename%, %_playlist_filename_ext%, %_playlist_folderpath% ) that are described in the docs aren't available from the context menu (unlike the other placeholders) and If You add them manually as a column there are never filled though a playlist is opened.
Thanks for caring.
I just loaded a playlist into MP3tag ("Kalle.m3u") and checked with Convert>Tag-Tag
So the variables are filled - I assume that they are read-only and only available in the context of a playlist but not generally, like e.g. %_counter% which also cannot be used sensibly in a column.
Thanks, now I understand how "it" works - You can obviously only show tags that are already written in the *.mp3 file in columns.
So as a test I definied a new field %playlist_release% definied an action from type "format value" (I guess this is the english name, "Tag Feld formatieren") and then I was/am able to see %playlist_release% as a column filled with the name of my actual playlist...
... but IMHO this wasn't what %_filename_playlist% was meant to do but it should so the name of the actual "loaded" playlist to the user
(In my test it would always show the last value written to %playlist_release% even if I opened it not from a playlist or from another playlist, but didn't start the formatting action...
Yes, I think there was a slight misunderstanding. Playlist-related information fields are only available when a playlist was loaded.
I'm moving this back to Support .
