bapu
I always leave the MIDI at the bottom. It's just how I roll.

Bottoms up, bapu :-))

Noel Borthwick [Cakewalk]
We'll look into it. There were quite a few updates to the synth solo behavior based on some lengthy threads on the forum. Also some old bugs with drum maps were addressed as part of us adding the VST3 multi MIDI bus support.

Thanks for the feedback, Noel. I'm just happy I finally understand what's going on. It's the "not knowing" that gets you. 
 
And thanks to all who took time to provide input here so I could figure out what I was doing differently. It should have been an  obvious thing to check in hindsight, but I can't think of another case offhand where track-order mattered. Also, I think I have at least one example where it's working with the MIDI track on top.
 
Cheers,
Dave

they should create a GS button for group solo switch and allow us to click off functions in a pop up on how it functions. Then say if I want a grouping of 10 or 20 tracks each with different sound sources that may or may not be midi based, could be audio or midi. If we could solo one track it should silence all the others in that group and not affect any of the other tracks outside the group.
 
Now that would be cool. also if we could create a virtual interface that would have 10 or 20 buttons ( act responsive and assignable) on it to quickly assign to tracks we wanted in the group and if there were rules for each button that could override the single channel rule so if I wanted to solo tracks 1 and 2 together that would be button one of the interface and then button 2 could be 3 or even 6 tracks and all the others in the grouping would remain silent when I pushed that button and then only the appropriate tracks would be heard in that group as I switched to another group of programmed tracks to solo etc. This would make sonar usable for live mixing so that we could record gigs. E drummers could use this to switch drum sounds on the fly like we guitarists switch presets on amps.
 
By the way 
 
I found a cool free midi plug in that will allow you to send a midi out to 3 different channels so you can layer 3 different drum programs together at the same time and you can do this for I think it will do 21 tracks. Have any of you guys tried it yet. its called note mapper http://www.vst4free.com/free_vst.php?plugin=NoteMapper&id=2169
 
Actually they have all kinds of midi plugins here http://www.codefn42.com/ was just reading about this last night but just clicked to go to the devs site just now. Man he has all kinds of stuff. http://www.codefn42.com/

brundlefly
After much fooling around, I've figured out the issue:
 
By default when you let SONAR create audio and MIDI tracks for a synth, it inserts the MIDI track at the bottom of the stack. I've always personally felt that $h!+ should flow downhill so I've always created my templates with the MIDI track above the audio outputs. Well, guess what... this breaks the new solo functionality. Take a working setup with an audio track soloed across a drum map, drag the MIDI track to the top of the stack, and voila!, no audio.
 
Also, this implementation still doesn't let you solo MIDI tracks in the PRV and continue to hear audio from a drum-mapped synth, so for me it's not a full solution even if they get the track-order thing fixed.

Thank you!  I thought I was going crazy.