Note velocities don't exist, cannot be created
Video Version
The problem is shown in this 1-minute video on YouTube.
Text Version
Because I never used the old version that much, I installed the new improved GarageBand 10.0.1
I've entered some notes using my MIDI Keyboard (Controller). Although their velocity values show when I hover my mouse over the notes in Piano Roll View, the "MIDI Draw" region underneath it is empty. Selecting notes in the PIano Roll does not help. The "Controller" popup on the left is blank. When I click that popup, I get a menu including Volume, Modulation, Expression, … Note Velocity, etc. But upon choosing one, the popup reverts to blank. I can draw lines using the mouse in the MIDI draw area, but the lines disappear when I release the trackpad to end them.
Someone please tell me what is the trick.
MacBook Air, OS X Mavericks (10.9), 13-inch