I'm just curious if you guys have had any luck with side-chaining with 3rd party plugins yet?  I can't remember all of the programs that I used to want to try it with, but stuff like Vocal Rider from Waves, and a few random compressors from other companies that had side-chaining built in, etc... They never used to work with Sonar, because Sonar wasn't able to interact properly with them.  I'M UNDER THE IMPRESSION that it was because Sonar didn't support VST3 plugins... But not 100% sure if that is an accurate assumption.
 
Is it safe to say that those side-chaining features work now?  Can anyone confirm this for me?  (I bought X3, but am still waiting to be able to access it)... So just trying to fill my curiosity in the meantime.  This is one of the biggest features I've been waiting for, for years now.
 
EDIT:
Actually, nevermind this post!  I just came across this post, which pretty much answered all of my questions... (So for anybody else that finds this thread, wondering about sidechaining & VST3) it sounds like Noel confirmed that you can now sidechain with 3rd party plugins right here... So yeah, I'm pretty excited about that.  Disregard my original question...
 
EDIT #2:
Eh, I guess I can't post links to another thread on these forums, it keeps getting removed... so... I guess just take my word for it... Noel said somewhere on these forums, that Sidechaining works... BAM!

Please, enlighten me. I have been totally unable to get Waves Vocal Rider to work correctly. It is the correct VST3 on Win 64 using X3.  In order for it to work, sidechaining  has to be working in it and the right side of the plug ( sidechain input) is grayed out.  I have spent over an hour searching this forum as well as trying different things. It is just as nonfunctional in X3 as it was in X2 so far.  I apparently am missing the magic password or something. 

Getting the same grayed out bits in my Renaissance Compressor. So far, no joy on the VST3 front.

Ah, the magic password is "X3b" I believe... VST3 functionality is supposed to be fixed this weekend... I'm ASSUMING it's going to fix the Vocal Rider issues.  The part I know is supposed to be fixed, is "loading VST3 plugins from projects you've saved, will resort to default settings for that plugin" pretty much eliminating any progress you've made..."  So that'll supposedly be fixed this weekend... I would like to ASSUME (at least hope) that sidechaining isues will be sorted out as well.
 

No, Waves Vocal Rider still doesn't work.  If anyone can figure out how to make it woprk correctly I would love to hear how.
 

This is a response to a friend of mine from Waves support a couple of weeks ago regarding Vocal Rider side chain not working.
 
First, please note that Waves hasn’t officially qualified Sonar X3 yet, we are working closely with Cakewallk on this one.
 
To your question, Vocal Rider Side Chain option works just like you said, using a Bus to send the musical content of your session to the Vocal Rider, not from any Bus but from a Vocal Rider SideChain designated bus. You didn’t see this bus as the Vocal Rider is probably open as VST2 and not VST3, only VST3 will allow you to use SideChain with Waves.
 
How to use set Sonar X3 to work with VST3 when available:
 
1.  Open Sonar X3, go to Edit > Preferences > VST Settings.
2.  Below VST3 Migration, check the two checkboxes
a.  Hide Related VST2 Plug-ins
b.  Replace VST2 Plug-ins When Opening a Project – This might cause corrupt GUI for plug-ins which were converted from VST2 to VST3 – You don’t have to check this one.
3.  Hit Scan.
4.  Close Sonar X3 and launch it again.
 
Now, add a Vocal Rider to your Vocal Channel, if you want to make sure it has opened as VST3, on the Sonar System Bar, on the plug-ins GUI, click on VST > Plug-in Properties, in the window opened, click on Details and check it was opened using the Waveshell-VST3 9.2x64.vst3 file.
 
If it is indeed VST3, when you go now to add a bus to any track in your session you will see a designated bus for Vocal Rider SideChain.  Now the Music SideChain will be enabled.
 
Again, as Sonar X3 is not officially qualified with Waves if you come across any problems we won’t be able to assist. We will release an official announcement when it is officially supported.
 
I hope this works out, have a great weekend meanwhile.
 

BTW..... This works great!  Thanks.

As long as you stay with the default out of box settings with X3 you should be fine with Waves support. 
Please also read this article which explains why this happened to you.