Due to software limitations on Phase Shift, I went ahead and split the chart for "Art of Life" (successfully!) into two parts (amazing chart, by the way!). The first half works perfectly, and I have the song_length adjusted for both parts to match how long they go for.
When loading "Art of Life Part 2" (which is its own separate song on there, but with the same song.ini and only the song length and preview time adjusted), I can load it, and the preview beforehand plays just fine, but it won't let me choose an instrument for any of the parts.
What am I missing here?