Huh, there once was a similar bug:
http://sourceforge.net/p/scummvm/bugs/2999/ , which was fixed at that point.
I can reproduce the bug begin there again in my CD version too, though. Damn.
Now, though, the reason seems to be different, because the case-insensitive compare is still in place, and it does find the correct track to sync against. In theory, at least.
It's waiting for the CD track to stop playing. It's only about a minute long, and if you wait that out, the voice lines will play. Still annoying, yes, but hopefully that workaround works for you.
For a proper fix, I will have to dive into the scripts and see what it actually does, trying to figure out why and how. And/or git bisect the ScummVM sources to see where it broke.
I'll look into this tomorrow, probably.