I have 4 soft synth tracks in a project - one is the True Pianos from Cakewalk and three are Dimension Pro 4 tracks, which are for trumpet, sax and trombone. My problem is that the three horn tracks are bleeding (faintly) into the True Pianos track.  The bleeding tracks are also out of sync (they are early). There are also 15 other tracks from a Soft Synth version of Roland Sound Canvas, which I know has some issues with Sonar,.  However, even if I mute all of the Sound Canvas tracks I still have the bleed problem on the True Piano track. The True Pianos track does not bleed into the horn tracks, not do any of the horn tracks bleed into each other.
 
Any suggestions?  I don't recall when I noticed this problem, but I don't think it occurred from the start, though I am not sure.
 
Thanks,
Dev

This sounds like something you have set up as part of the routing of the project. If you create a clean project with the same instruments do you have the same issue? 

This can drive one crazy trying to figure out. DAW tracks cannot "bleed" onto each other like physical tape tracks can. There must be a SEND routing or other phenom going on.
 
Do one or all of the following:
1. Solo each synth leaving each previous one soloed until the effect shows up
2. Check the output of each synth and reroute them to your audio interface if not already there
3. Delete or mute any SENDs

On the existing project there are 4 soft synth tracks, and ALL of the horn tracks bleed faintly into the True Piano track.  I soloed each to verify.  None of the horn tracks have bleed from any of the other tracks. So I created a new project with one True Piano track and one horn track.  Everything was perfect - no bleed.
 
I then went back to the original project and set the output for the horn tracks to none.  I still heard the horn tracks on the Piano track, though it only sounded like the sax (it was very faint, so not sure).  How can I possibly hear sound on the Piano track when all of the outputs on the other tracks are set to none?  There was no send on these tracks and I turned off all of the FX.
 
I then thought I would paste all of the tracks into the new project since I wasn't getting any bleed.  This created a new problem.  Though I copied track automation (which for me is just volume), when I pasted into the new project the volume automation was added as a separate track, so it didn't affect the original synth track like it should.  This won't work because I have A LOT of volume fades in the project!
 
I did notice one difference in the new and old projects.  When I selected outputs in the new project, some the drop down options were "Master, Metronome and Preview".  In my old project these options were replaced with "A, Aux1 and Aux2".  The new project has Master as the output for both tracks, but I don't have the choice to select Master in my old project.  How do I change my old project so that I get the same output options as my new project?  Do you think this could be the problem?
 
This is SO frustrating!  Any advice anyone?
 
Thanks,
Dev
 
 

I had the same issue, in fact I've had a lot of odd buggy issues when using aux tracks. Also I couldn't even update Big kick to the latest version (https://www.pluginboutique.com/product/69-generator/879-bigkick) as when I did, it messed up routing of aux tracks in other projects, making them silent. Lots of buggy things still in Sonar and we are now left in the sh*t! So much for lifetime updates & fixes, really annoyed.

Your tracks or even the whole project could be corrupted. I'd start fresh with a new project.

None of the fixes worked, so as per the last post, i Just started a new project.  I had to copy and paste all the tracks, and they usually lost the volume adjustment, so I had to mix all over again.  However, it was worth it, there is no bleed.  Just have to chalk it up to corruption I guess.
 
Thanks for suggestions,
Dev