I have a piano/keyboard (HP 137R Roland Digital Piano) hooked up (via MIDI to USB) to my Mac Mini computer and it has worked fine with GarageBand (10.1.6) and Synthesia (10.3.4077) for years.
Then yesterday I installed MacOS Mojave thinking dark-mode would be kind of cool. To be safe, I even googled to see if Mojave messed with GarageBand and didn't seem to find any red flags, so I went ahead and installed it.
Now neither GarageBand nor Synthesia recognize that there's a perfectly good keyboard hooked up for MIDI input. Please help me. Do I need to undo the switch to Mojave or something (if that's even possible)?