Huh. I thought this would be a C2 bug, since it broke after the update, but apparently it's a problem with this event line:
<img src="http://i.imgur.com/5OCQkVV.png" border="0" />
The logic is that, if MusicB volume is 0db, it resets the fade variables. Apparently C2 thinks that MusicB volume IS 0db, even though I just told it to start playing the song at -30db.
I'm unsure if it's a bug in C2 or the code, now...
I did fix it by doing this:
<img src="http://i.imgur.com/MOQEUQw.png" border="0" />