Kind of weird. I can play each note on my keyboard once which will produce the note sound, and then the keys don't trigger sound anymore. As well, the software doesn't follow along when I hit the note it's asking for during the scale practice. This is on the latest 1.0.3 mac release.
Edit: Tested a little more and I found something interesting. When I use an Alesis Q88 it has the issue above. To add on to the issue, the notes are elongated almost as if the sustain pedal is engaged. I don't have a sustain pedal hooked up. When I use the Komplete Kontrol M32 the program works as intended. Notes are not sustained either.