All the juk-created tags I've seen were AFAICT perfectly correct UTF-8 encoded id3v2.4 tags according to the http://id3.org specs. Yes, id3v2 and xmms and just about anything else don't seem to deal well with these but I wouldn't call a deficiency of these other apps a bug in libtag1 or juk.
BTW 1. I really wonder if this is the right bugreport to discuss this, though 2. I've never seen v2 tags disapperaing when using juk, so maybe it is the same problem -- MichaĆ Politowski Talking has been known to lead to communication if practised carelessly.
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