I've been plagued by this since I can remember. I can transcribe bass lines and melodies pretty well given enough time. (my eartraining has atrophied a little) The thing I have a very hard time with is hearing the harmony. I used to easily pick out major and minor chords as long as they were in first inversion. Once you invert the chords or add tensions I get lost. So, for those who can do this well, how do you practice it?