Reproduced, thanks. Tracked as http://www.ventismedia.com/mantis/view.php?id=9247

Example:

File name is

써니힐 - 사랑밖엔 난 몰라

Autotag by Filename using <Artist> - <Title> results in

Title: 사랑밖엔 난 몰라
Artist:

However if the file name is 써니힐 (Sunny Hill) - 사랑밖엔 난 몰라

and you Autotag by Filename using the same criteria, you get

Title: 사랑밖엔 난 몰라
Artist: 써니힐 (Sunny Hill)

Please post concrete example of such file name, thanks.

Tag from Filename containing Title and Artist in unicode characters results in proper tagging of title, but not the artist. However if there is mixture of Ascii and unicode character in Artist name (ie. 빅뱅 (Big Bang)), the the Artist field will be tagged correctly.