Previous thread was locked, can't add to it.    But it's happening again, right now; this is not a midi import issue, that was a red herring.   Using a project I've been working on for several days.  
1)  Paste Special does NOT open a dialog window.
 
2) It pastes a selection into a different track than is selected
 
3) It pastes the selection into a different time than is selected.  
 
Screenshots follow. 

Give a recipe starting zero, with the minimum number of steps needed to reproduce and I'll see if I can.

Shot 1: after doing it 7 times... far right, event list view, circled.   NOT pasted at Now Time, NOT pasted into selected track, and NOT pasted with a Paste Special dialog.

Screen view 2:  the Paste Special about to be clicked ...
 

view 3, after two more pastes.  Note different Now Time, but the paste went to the same place, same non-selected track. No Paste Special Dialog.   No paste to Now. 
 

Again, I am not certain this is new with Cambridge, but I have NEVER seen it before and I use the software daily. 
 
A guess as to why: too many midi 'clips' for the software to handle (ie a bug deep inside) causes some unrelated problem which shifts as the compiled code changes size.    The 'too many clips' problem is very very old, causes crashes (Sonar 3, 5) and interface disorder (screens that don't show what they should show) in X3.   
 

I'm afraid the recipe to reproduce is going to be: use the software a lot in one session in a big project.   But I'll close it now, re-open, and see if it will come back.   My guess is no. 
edit - my previous experience with this problem, the paste occurred in a new track at the end of the project.
this time, I believe, the location for the paste followed a similar rule: it went into the last track I had created a clip on (by input through PRV).   I'm not certain about this, however ... the disruption of the bug made me forget exactly what I had been doing.

As expected, paste special works correctly again after saving the project to a new name, closing Sonar, opening sonar, and opening the project. 

Please post these kinds of posts in the Sonar forum to start with - thank you.
 
Bob Bone