Anonymungus!
   What I was referring to was: I select some notes in the PRV, cut or copy, switch to a different track from the PRV track menu, then paste. It pastes to the original track. 
   Often I want to select a harmony & just move the harmony to a different track, and do it all in the PRV to make it nice and simple.

I agree - I see this also. However, I think there is a little twist to the explanation. Make sure to pull out the track selection on the right side of the PRV (lists all your chosen instruments). If you select a destination track in that instrument list, you can paste into a different track.
 
I actually think there is a bug here. I have never, until today, been able to paste into anything other than the source midi track without using Paste Special. So maybe something got fixed.
 

AllanH
However, I think there is a little twist to the explanation. Make sure to pull out the track selection on the right side of the PRV (lists all your chosen instruments). If you select a destination track in that instrument list, you can paste into a different track.

 
Exactly! That's what I meant.
 

I actually think there is a bug here. I have never, until today, been able to paste into anything other than the source midi track without using Paste Special. So maybe something got fixed.

 
I did it with Ctrl+V...so maybe something did get fixed.
 
One thing I've noticed about the rolling updates that doesn't get mentioned is sometimes, fixing something fixes something else of which the Bakers aren't even aware, because it wasn't what they were trying to fix. It's sort of the opposite of fixing something that breaks something else.
 
 

Anonymungus!
   What I was referring to was: I select some notes in the PRV, cut or copy, switch to a different track from the PRV track menu, then paste. It pastes to the original track. 

 
So you're using the "Tracks" drop down menu at the top of the PRV window, in which you change tracks by the "Pick Tracks..." dialog  ?  (Another way to skin the cat !)  I see what you mean about it not working properly.  If you pick a new track, the display changes to the proper track and you can enter notes, select, copy, etc.  but if you paste the notes go into the previously selected track because it's still the selected one.  Pick Tracks doesn't cause the new track to be selected -- until you touch a note that is already in the new track at which point it becomes the selected one.  This looks like a bug to me (EDIT :  maybe not, see below).

   Well, thanks for the replies. It would be real simple if, when you choose a track from the PRV track menu, that track automatically becomes the 'selected' track.

Paul P
Pick Tracks doesn't cause the new track to be selected -- until you touch a note that is already in the new track at which point it becomes the selected one.  This looks like a bug to me.

 
I don't know. Depends on whether the rationale for picking a different track is for diagnostic purposes or for editing. I'm going to check into this further...my head is about to explode right now.
 

 
Help says this on the "Tracks" / "Pick Tracks..." dialog :
 
"Choosing the Pick Tracks command in the Piano Roll, Event List, Staff, or Lyrics views opens thePick Tracks dialog box, which allows you to choose which tracks’ data you want to display in any of the above views. To choosetracks to display, simply highlight the names of the ones you want to display. You can select non-adjacenttrack names by CTRL-clicking, and you can select adjacenttrack names by SHIFT-clicking or dragging."
 
It talks about 'displaying' data, not doing anything with it.  This dialog allows you to select more than one track to display, but only one track can be selected at a time, so which one would it be ?
 
It might be best to use the Track Pane on the right of the PRV instead of this Tracks menu.  You'll have to have all tracks show in the track pane (select your track numbers before opening the PRV), but you can hide the notes for each track you don't want to appear.  Then it'll be an easy matter of selecting the track you want.
 

Funny I was having trouble with this as well. I noticed when I started a new project and just entered a few midi notes that I was able to lasso select and use ctrl-x to cut and then choose the next midi track clicking its name in the PRV track list and use ctrl-v to paste. It worked fine.
 
However I was trying to do this very thing in an existing project and I just verified that it does not work and always pastes the data back into the original midi track.
 
Now I need to see if I can figure out why one works and the other does not.
 

OK. I think I have sorted out why my existing project did not work like the new one did.
 
In my existing project I had 2 separate PRV windows open in the multidock. That seem to be what was causing the trouble. I closed both PRV windows and then opened and empty PRV and selected the same tracks I had selected before and was able to cut and paste between the different midi tracks by selecting the track on the right of the PRV.
 
This is good to know I was going nuts editing horn tracks the other day to get the notes moved into the correct articulations.
 
Thanks for posting this question.

There seems to be growing list of inconsistencies between behaviours within the PRV depending on weather it is docked or undocked.  In most cases that I have encountered problems occur in the docked state. Fingers crossed this is getting some attention in future updates as the multidock is a great feature when screen real estate is is at a premium. 

To do what you want requires some babying of sonar.   You have to be sure not to select what you don't want, and for that you must go to the track view and select tracks, can't be done in PRV.      Then, unfortunately, you have to be careful that having selected a track the selection criteria don't change.   For instance, 'lasso' a group of notes to copy and paste.     Looks like you just have notes, right?     But once you go to track view and indicate tracks, suddently you've got a time-range selection, with everything in that range selected (controllers, patch changes, pitch wheel, aftertouch, etc etc).     A complicated PITA, with what you want to do and what's possible two different things.
 
It's my pleasure to be here on the forum with this advice because of a recent crash, losing a couple hours of painstaking work, from exactly this kind of bug in Sonar.     Select, copy, cut, paste: THERE ARE BUGS.