Update:
I re-downloaded the repository (team is using Github). Switching to an older commit (when audio was working) does not solve the problem.
However, when I make a build, all of the audio works as expected, which is really strange.
I’m going to work backwards - reinstalling the FMOD Unity Integration first, then the Unity Editor, then Studio if necessary.
If anyone has run into this problem before and has advice, I’d really appreciate it.
SOLVED - A re-install of the Unity Editor seemed to fix it.
For the sake of posterity, I’ll will say there’s a non-zero chance that I had “mute audio” selected in the Unity Game Window. At this point I don’t know for sure.
This is a really easy thing to miss - if you’re having this problem, first do a quick sanity check to see that it is not selected. You might save yourself a few headaches 
