Hi REZA,
As you know I have the same problem as you about the master fader.
This is randomly if the master fader operates in accordance with the Sonar fader or not.
There are two days I was working on a new project that the master fader did not want to cooperate. I leave it like that and do not worries me.
Wanting to add the drum (Addictive Drum) I plug my midi controller (Roland A-800 Pro) in usb . Sonar asks me if I want to add the controller. I said yes.
I go into the options ticked the boxes in the options MIDI devices.
I click apply and Bang the master fader goes to zero and is now
synchronized with Sonar the master fader.
I do not know if your side it does something?
Thanks.