The only reason I love using Sonar is that it is not only intuitive but convenient, especially when handling notes in the staff window. So, copy and paste is the most used work as of me. However, [<font]paste does not work without several tries in the staff window, or nothing happens.  Of course, I tried every option including copy special, paste special.
 
In this video example, I made just a single track and it was in focus as well while editing notes. 
 
 
Actually, Sonar 7 and Sonar 8.5 do not have such issues. Cakewalk has released patch 'e' for Sonar X3 so far, but it didn't fix the bug. 

 
-----------------To Work Around This Problem---------------------
There are two solutions.
1. 'Spilt instrument track'
2. Check 'MIDI Source', 'Synth Track Folder, and 'First Synth Audio Output' in the 'Insert Soft Synth Options dialogbox'. You can open this dialogbox by pressing 'B' and clicking 'the insert synth options icon'.
 
 
 
Conclusion:
Originally, the synth track consists of two parts, an audio track and a midi track for the VSTi. And on the midi track, we draw notes. By the way, the simple instrument track has only one track, which means it contains both parts implicitly. So, the simple instrument track does not seem to recognize the midi track properly that does not exist definitely, it ends up with not knowing where to paste. Since the simple instrument track is combining two tracks, it should have processed the paste work accordingly.
 
The funny thing is that I can do every other job in the track, like drawing, cutting, and so on. Only paste does not work correctly. It is not a matter of checking if the current track is in focus. This is totally the track's bug. I also found this problem has appeared since Sonar 8.
 
 
 
 
 
 

Sonar X3e is the last version in that release. There will not be any more updates to the Sonar X3 release.
The new release of Sonar is Sonar 2015 Artist, Professional or Platinum.

Welcome to the forum BC399. As Mike points out there will not be any further development for X3. I would recommend that you upgrade the new version.  

Paste pastes to the track that is in focus in the track view, without any dialogue box, annoying I know because I forget as well, paste special (Ctrl-Alt-V) opens a dialogue box which gives you the option to select the destination as well as other options.
 
While it is frustrating and one would think that the focus would be on the track you are editing in the staff view it is not.  This has been the same in all the X versions and persists in the latest versions.

I have always thought that it was just intuitive
to change "select" cues in all views in realtime,
as you move about a program.
 
(i.e.  if I change tracks in PRV, that's the track that should be in focus
when I return to the TV, SV or CV)
 
DAW follows ME, not the other way around.
 
Sonar is the only program I've used that doesn't
behave in this manner.
Odd.
 
Mel

It works that way in the main views (TV & CV) but not in the sub, or editing views (prv & staff).

I agree the copying and paste function in X3e is frustrating.  I CLEARLY have a track highlighted and the software winds up pasting somewhere else.  It may be the most annoying thing of X3.  ...but I live with it.

I didn't watch your video but I thought it was buggy until I realized you have to pay attention to the selection range in the timeline. Sometimes the selection range is one amount but you can forget to double check it and end up with something else.
 
HTH

I am having the same problem with copy/ paste not working.
VERY BUGGY!!!
 

Please start your own thread and describe with exact steps what you are doing and what you are expecting to happen/does happen