Got a Cowon D2+ 16GB. It seems picky about mp3 tags and “bad” tags make it show up Unknown for everything under the Music Library even if only some of them are bad. Sometimes though, like 1 in 10 tries, it showed most of them correctly. This is a real pita and I though the thing was broken at first.
Using foobar2000 or mp3tag we can retag mp3 files correctly. Using only APEv2 seems fine.
I did not have any problem with flac files.
I should soon upload some ogg files in it and see if there’s any problem.