jazzman16777
 
Major irritant 3!
Audio sustain on certain tracks drops when a sudden event on another track (Like a drum hit) occurs.
Guitars ringing out as new drums come in for example. Drop in audio is noticeable enough to require me to
layer something over it or try to fix using clip or volume automation to cover up problem...sucks.
My first guess might be a sudden drum hit pushes mastering compression harder (I do sum everything to a single
Mastering Bus)...but dammit! I like the comp where it's at! lol
 
Any suggestions out there? 

This isn't a bug - this is just how compressors work.  As Mr Anderton pointed out, you may have better results with multi-band compression.  Or, do your heavy compression on the tracks that need it, and take a more subtle approach on your busses.
 
This is about learning your craft.  You'd have the same problem in the analog world.  Nothing to do with Sonar per se.

Gregkonji
How about a speed comping issue as well?  I have this month's release but I haven't upgraded to the latest patch.  Last night when I clicked shift + space bar to loop a take, the take was the only thing audible.  All the other tracks were inaudible in this mode.  I tried changing my dim solo setting in preferences from where I had it at -6db to 0db which didn't help. 
 
I can't think of any other settings that would do this.  Am I missing something? 

There were upgrades to Comping/Take lanes in this past months update.
things have changed a bit / for the better.