Chord playback broken when changing to instrument with different tuning

If I assign chord symbols to a notation written for flute (C-tuning) and then change the instrument to, say, tenor sax (tuned in Bb), the notation as well as the chord symbols are correctly transposed in the score, but not in the playback. To reproduce this, do the following:

1. Create a score/stave with C-tuned instrument (flute, voice...)
2. Enter a note 'C' and assign a chord symbol (such as C^7) to that note.
3. Change the instrument of that stave to a Bb-tuned instrument. The note is now, correctly, shown as 'D' and the chord as 'D^7'
4. Play the score, and you can notice that the sax plays correctly concert-C, but the chord plays as concert-D^7. Very annoying!

Hint: I then discovered that the mixer has a track called "Chords.Flute". I didn't find any way to modify that track setting (it would anyway be quite a clumsy workaround), but it might give a clue to track the bug. Apparently changing the instrument of a stave doesn't synchronise the chord playback track.