Make playlist from all files / selected files currently always creates an M3U file with ASCII encoding which messes things up if any of the included filenames use non-ASCII characters.
What you could do about it is make Mp3Tag automatically create an M3U8 file instead of M3U if any of the filenames/artists/titles include non-ASCII characters.
M3U8 is Unicode version of M3U. It uses UTF-8 encoding (without BOM) and .m3u8 extension. Apart from that their internal structures are exactly the same.
Foreign letters in the m3u get garbled completely or at least lose diacritics, which makes the filenames (paths) wrong and music players can't play them because they can't find the files.
Thanks, I didn't know that. I tried it and it works.
However, users shouldn't be expected to check all filenames before creating a playlist to know if they need to change the extension; besides it's easy to miss a single diacritic in a whole album.
Since Mp3Tag already knows how to write m3u8 files, using it automatically if there are characters in filenames/artists/titles that fall outside of Windows-1252 (or ISO-8859-1, or whatever encoding is used in m3u) should be a default procedure.
OK, I've changed the extension to m3u8 in Options → Playlist → Filename of playlist so now it always saves m3u8 playlists.
Maybe using "bug" here is a question of semantics, but I don't see how writing m3u format by default, which easily breaks some playlists, is the best solution for Mp3Tag.
Instead of relying on the user to change the extension in the Options, smarter playlist handling would be to automatically write m3u8 when needed.