The bug on KDE is at http://bugs.kde.org/show_bug.cgi?id=136929 I'll post a patch here... I can also post the e-build, it is just 1.4.3-r1 with one additional patch (ask if you want it).
Created attachment 101651 [details, diff] Patch to take out the check for canDecode. This is the fix that I am using for the bug. It basically always allows the files to be added to a playlist, which in my opinion is better behaviour. Files that cannot be played are greyed out. This also works around the unknown bug that causes amarok to throw away 'flac' files that it can actually play.
No. Remove the ID3 tag in front of the FLAC file, or wait till 1.1.3 snapshot.