I don't know what I changed. I used to have no problems with this:
 
1. I plug into my guitar rig and then run cable out into the focusrite 6i6 (left or right) (never a problem before)
2. Make new audio track
3. assign input to focusrite usb asio (left or right)
4. make sure input echo is off (or I'll get a delay)
5. no signal coming from track
6. arm track and see signal but hear nothing still
7. record and play guitar anyway (hearing nothing)
8. actually get a recorded track to hear afterwards, but you really need to hear it while recording right?
 
I used to be able to hear the incoming signal before and I never turned on input echo unless recording midi.
 
Please advise
Thanks
 

I believe that unit has MixControl. If using the main outs you will need to set the outputs to the active mix and have one fader set to analog 1 or 2, depending on which preamp you are using. Then you can blend the DAW fader with your direct monitoring path (analog 1/2) and hear both on the main outs.

I forget offhand if the "ultra low latency tracking" preset will set all of those automatically, but those presets may be how it got shifted on you.

I do now have sound by assigning the monitor output in the focusrite control panel to a custom mix that I can pan the signal and adjust levels to the main mix within the focusrite screen. What I can't do is adjust the audio track fader and pan in sonar on the track itself. I didn't have to go into the focusrite control panel to make these changes before. Very strange. I wish I could figure out how to use the track fader and pan like I used to simply by plugging into the 6i6, hear the signal, pan and adjust the fader, arm and record. 
 
Changes....turn and face the strange
 
 
 
 

What I can't do is adjust the audio track fader and pan in sonar on the track itself.

If you are recording or just want to jam and hear yourself, then Sonar has no control over this. Volume and pan is controlled by everything before it hits your converters in your sound card.
 
CJ

As CJ said, the controls in Sonar have no bearing on recording levels or panning.This is done in your interface. And as you now figured out using Mix Control to set this up. I have never had to touch mix control , I just leave it alone so what ever the default is works for me.  I just installed it to a new Laptop and never even opened it. Only thing I use it for is setting the Buffer.