I decided to post it independently from my upcoming review of automation in Sonar because it is rather an old bug on its own.
I noticed it since 8.5.3 and it persists in X3d (did that ever worked at all?)
Automation snapshots don't work with soft synths parameters, armed in synth rack
To reproduce it: insert any soft synth into synth rack, click "show assigned controls" and select any available parameter from context menu (cutoff, for example). The knob appears in synth rack with parameter's name and value. Then you can enable automation for assigned parameters in synth rack and write it, without pressing record button or enabling automation on track. Just press play and rotate the knob, very simple and handy.  Then, right click on the knob. What do you see among other options? "Automation read enable", "automation write enable" and "AUTOMATION SNAPSHOT".
Expected behaviour
From working with track envelopes, we know what the last option should do - you move parameter, that is being automated, to appropriate value, you press "automation snapshot" and voila - the envelope with a new "jump" point for this parameter appears on track. IMHO, this is the best way to write "jumpy" envelopes for abrupt parameter changes in one action. (when you do it manually, you need first to create an envelope, then create a point, then drag it to appropriate time/value (not always so easy to put it right), then choose" jump" for the previous envelope section). That is how automation snapshots work with automatable parameters in track view (volume, pan etc)
In real life
Shortly - it just doesn't work with synth parameters in synth rack. Assign parameter in synth rack, click "automation snapshot" - and nothing happens. The option is there, but it does not work.
 
Please confirm.
 

Are you able to write this in the form of a list?
i.e. like http://forum.cakewalk.com/Show-Velocity-on-Selected-Notes-only-doesnt-work-properly-CWBRN22587confirmed-by-CW-m2962623.aspx
 
I think I will be simpler for me to follow anyway.

Thanks...

ОК, you are right.
I suggest not everybody is familiar with automation snapshots, so here are detailed steps to follow:
 
Example of properly working snapshot feature (this works for VST):
1. Insert audio track.
2. Insert VST in track's FX Bin (let it be Boost11 for simplicity).
3. Make sure "Display - Module options - Fx  - Show assignable controls" is selected in track inspector.
4. Go to assignable controls module in track inspector, right click parameter that you want to automate (let it be "Boost") and select "Automation Snapshot".
5. Result: the automation envelope for "Boost" parameter appears on track with "jump" node that corresponds to current Boost value.
 
The way it supposed to work with VSTi:
1. Insert any soft synth in synth rack.
2. Click "Show assigned controls" in synth rack to expand assigned controls panel.
3. Right click on panel and select any synth parameter you want to automate. Corresponding knob appears on panel.
4. Right click on the knob and select "Automation snapshot".
5. Nothing happens, automation envelope does not appear as expected
 
 
 

Show Assignable Controls is ticked, but I'm sorry you are going to have to educate me about the assignable controls module, can't see that in the track inspector. Probably in front of my nose, might have to post a screenshot in order overcome my blindness.
 
Sorry...

Addition on this matter: on instrument track assignable controls module in track inspector always shows CC values, like it does on midi track. Even if track inpector is expanded so that audio/midi tabs are available, no matter which you select it still shows CC values on audio tab. (one should expect it will show selected VST controls instead) So the only way to get to VST's assignable controls is to split instrument track. I consider this is another bug - by default instrument track must display assignable controls for VST which is currently selected in FX bin. and switch to midi CC values only when I choose midi tab in track inspector.
 
What's even worse, assignable controls module in Inspector now is the only way to get to the VST automation snapshot feature (aside from hotkey combibnation). And there's no GUI functionality at all to take multiple parameters snapshot. 8.5.3 had a dedicated button in automation toolbar for this, now its gone. In the meantime Mix module in X3 Conrol Bar has an empty space just for one button over the "clear all automation write enables" button, so why not put "snapshot" button in there?

 I marked this module in red, it's just under the FX Bin module

My bad I had a properties windows overlaid on top... OK picking it up...

So this is the result in X3D:
 

 
 
 
 
 
 
 

Yes, you did it correctly. That's how it works with VST's. Now try it with synth

The first step should be to undock the synth rack.
Issue confirmed.
Would you mind reporting this to cake with your steps (we're just interested in the steps to repro the actual issue) via problem reporter:
http://www.cakewalk.com/support/contact/problemreport.aspx
 
And it would be good if you could post the reference number. Thanks.