Playback and MIDI input disabled after upgrading to Sierra

Just loaded the latest update to OS10/"macOS" only to find it seems to have broken MIDI support in MS. In MS Preferences>I/O, all of the drop-down menus for PortAudio do not populate even though both the keyboard and IAC driver show up as online in the system audio MIDI setup. It was working just fine yesterday, so I'm hoping somewhere there's a "make this work" switch that just got turned off when OS10.whatever left the room...