If no notes are selected, then the velocity pane either show ALL velocities or NO velocities. 
- The old Sonar showed ALL velocities, which was useful (and matches the documentation). 
- The new Sonar shows NO velocities, which is useless (and violates the documentation).
 
Can you please explain why you think showing NO velocities is "no less functional" than showing ALL velocities?  To me, an empty velocity pane has no value, since it contains no information, and cannot be used to change velocities.  What function does an empty velocity pane have?
 
To me, this is clearly a bug, caused by post-X3 developers either:
 
a) introducing a logic error which breaks the existing note selection logic
or
b) failing to correctly and fully re-implement the note selection logic when doing a rewrite
 
I'm not sure which happened, but I sure hope they fix it soon!

In order to select all notes in the track you have to click the track, or inside the piano roll, and then click CTRL-A.
 
Those are extra steps, and when you are editing during playback (as I do), extra steps waste time, increase the chance for error, and increase the chance that the PRV has scrolled the notes you want to edit out of view, thus requiring you to interrupt playback in order to rewind to the section of the song you missed.