Indeed, that is the puzzle here. Sometimes it works, other times it does not. Until now I have not found any pattern. One time it works, the other time it does not. Whenever it does not work, opening different projects or creating new ones does not help. However, without restarting Windows or toggling the power on the console, restarting Sonar can do the trick (sometimes!): suddenly it behaves as intented. As you said, I am going to keep an eye on this one as well.

The master fader thing is a know issue intrduced in X1 D update .... alternative i tried and validate is the Avid stuff , i ask Jim from ssl to have an eta on sonar integration and it's not on the menuas its silence implyed ....
 
 The market is sure waiting for a 16 fader console around 2 K with all the basics needed , no soundcard and all ... the VS 700 could have been a classic ... some in the same style would , but manufacturer seeems to prioritsed instant profit with the less investements .... yes music bizness , is a bizness

As has been mentioned by Zo, the intermittent master fader bug actually first appeared in an earlier version of SONAR. One of the Cakewalk staffers posted a workaround in the V-Studio hardware forum that still works fairly reliably:
 
Hold down the Ctrl key and then click the Reset MIDI & Audio icon (next to the Audio Engine icon) to get the Master fader to wake-up. Sometimes you may have to click it more than once, but once its starts working, its solid throughout the active session.
 
-e.B

I would like to see that one on a screen shot - if possible - trying to see in "my head" where your talking about it. Not in front of my computer right now😳

Yes As EBlue mentioned , this is a known issue and I already had a long conversasion with Paul, Lyle C and Adrian (from Roland) and they asked to contact cakewalk, which i did but also cakewalk says this issue has to fix by Roland ...long story short , no one wants to help and fix the bug. it started in my end when i upgraded to win 8.1 and sonar x3. but i think problem is not sonar , it is the control surface driver issue for win 8.1.
here is the conversation:
https://rolandcanada.zendesk.com/entries/39337693-V-studio-700-master-fader-issue
Also here:
http://forum.cakewalk.com/WIN-81-AND-SONAR-X3D-VSTUDIO-MASTER-FADER-ISSUE-m2976399.aspx
 
As a fully compatible control surface with sonar it would be better for both company to keep going and improve it. even they could make the 8tracks fader add on to expand the mixer like Mackie but   for some reason both preferred to abandon the whole project :)
Compare Roland _in the mixer and control surface section_ to any company, they are always behind and would not support their products after a couple years passing from release date. most of the successful companies provide new drivers and update as soon as a new OS comes to market but Roland even sometimes give up to release the new compatible drivers. For example: for the v studio 700 R and 700c, you can't find any proper driver for mac , even older OS. 
I don't know maybe I am wrong but personally i have not have any good experience with Roland.I had vmc7200 set and now have vs 700 set which both are discontinued.
 

Regarding the VS-700R interface, a Sweetwater tech had a theory—based mainly on the process of elimination—that all or most of the weird issues I have had with Sonar are related to the VS-700R interface.  His theory was that some bad code in the firmware caused a lot of issues.
 
I never believed that and never even powered up the MOTU interface in my rack.  This thread has made me think that maybe I was too hasty in my judgment.

Well, I like the Nucleus and considering that it includes an interface, the price is not ridiculous (though not cheap).
 
The problem is, I still feel like I am going to be struggling with trying to set up some kind of custom programming to make it work with Sonar.  The discouraging thread below is a bit old but I haven't heard any updates.
 
http://forum.cakewalk.com/SSL-Nucleus-with-Sonar-X1-from-the-horses-mouth-m2378785.aspx
 
 

Zo
The master fader thing is a know issue intrduced in X1 D update .... alternative i tried and validate is the Avid stuff , i ask Jim from ssl to have an eta on sonar integration and it's not on the menuas its silence implyed ....
 
 The market is sure waiting for a 16 fader console around 2 K with all the basics needed , no soundcard and all ... the VS 700 could have been a classic ... some in the same style would , but manufacturer seeems to prioritsed instant profit with the less investements .... yes music bizness , is a bizness

Then maybe I was a Lucky guy. The master fader issue never appeared before my latest update to Sonar Platinum. Since I, apparently, screwed up in my upgrading process, I am not inclined to seek the fault primarily at the drivers or plug-in. Moreover, it is a slight inconvenience at best, not a pertinent reason to throw away my investment in an otherwise amazing control surface.
 

konradh
Regarding the VS-700R interface, a Sweetwater tech had a theory—based mainly on the process of elimination—that all or most of the weird issues I have had with Sonar are related to the VS-700R interface.  His theory was that some bad code in the firmware caused a lot of issues.
 
I never believed that and never even powered up the MOTU interface in my rack.  This thread has made me think that maybe I was too hasty in my judgment.

When I switched to TASCAM's US-4x4 SONAR X3e became much more reliable. With Platinum, I'm still waiting for my first crash.

Anderton
 
When I switched to TASCAM's US-4x4 SONAR X3e became much more reliable. With Platinum, I'm still waiting for my first crash.

 

 
 
Then again the truth is the truth but I fancied pasting something