In-app piano almost inaudible

I just installed MS-4 and all the sound files. I opened a new score, opened the in-app piano, and the volume is almost silent. It played just fine in prior versions of the app no matter what was on or missing from the score. Any ideas on how to make it audible? I assume this is a bug? I have already:
Checked my computer speakers and volume/mute. It's functional, at 100%, and not muted.
Restarted the app.
Tried another new score using the settings that pop up as default.
Adjusted the mixer to top volume.

*Edited to add: the sound that does come out is warped. I'm trying to create a vocal score, and the noise the piano does make (inaudible below middle C) sounds like a slo-mo slide whistle.