No playback

Hello all! I'm at my wit's end at this point and would greatly appreciate assistance.

I recently (today) updated Musescore from 2.0.3 to 2.1 via the automatic update feature. I'm running on Mac OS X El Capitan 10.11.6. After the update, I noticed that playback had gone completely silent. The tracking bar still runs across the measures and the notes light up as if they're being sounded, but no audio comes through. It isn't any one specific file; any file I load up is silent. I ran the gamut of suggestions that I repeatedly came across while searching the site here. The volume sliders on both the Synthesizer and Play Panel are above 0. The Synthesizer displays "FluidR3Mono_GM.sf3" in the soundfont list as it should. My I/O settings in "Preferences" are set to Port Audio, API: Core Audio & Device: Built-In Output, as they were before I updated. I tried adding different soundfonts. I've done a factory reset multiple times. I've uninstalled and reinstalled the program multiple times. I've checked that MuseScore is looking in the right folder for soundfonts, and it is. Nothing is muted in the Mixer, and my system is not muted either (I'd be highly embarrassed if that was the case). And to top it all off, the strangest part of this is that the metronome continues to make noise just fine. I've run out of options and am quickly running out of patience. Please please please help! I am more than willing to try any options suggested. Thank you.

EDIT: I guess I should add that clicking on notes already entered does not cause them to sound either. They should be making noise, as I have "Play notes when editing" checked in the Note Input tab in Preferences.