[Solved] Gain Loss at the Master Bus. Help!

are you sure the pro channel is not active ?
 
your photo is very small so its hard to make out what the -7.9 is ? (underneath the vocal reverb)

Do you have both buss meters set the same?
 
 
Edit, also I had stuff like this happen in 2016 10, I had to rollback...

The obvious variable you haven't taken out of the equation for troubleshooting is the limiter. Bypass it and verify that the level's exactly the same as what the track is reporting.

Yes, you are correct that if you have a track running at one level, with no effects or gain adjustments or panning routes to a bus, the bus shows the same level.
 
You are missing something.
 
There is an input gain on the track and the bus.
 
Any effect, in the FX Bin or the Pro Channel could change the gain.
 
You can rule out FXs by clicking E  to bypass all FXs.
 
Once that's done, there should only be the track routed to the bus (it's volume fader, gain and pan) and input gain on the bus (fader and pan can impact output level but not input level - you can set the meter for either).

Pan laws? You are also sending a panned mono track to a stereo buss.

The pan law theory doesn't, er, pan out because even if you were using the -6dB center pan law that would not account for a 7.5 dB drop.
 
Completely remove (not just bypass) all effects and see if the problem persists. Although unlikely, make sure there aren't any clip effects. Also verify that the track interleave is set to mono.
 
I am suspicious of the track effects because one or more of them may be forcing interleave toggles, which happens when you mix and match mono and stereo effects. If any of them were to introduce a phase shift, that could reduce the level. However, I'd expect that kind of problem to be audible, as a thin-sounding track. It's also possible that one of them is causing a level drop even when bypassed, an unusual but not unheard-of behavior.
 
 
 

 I FIXED IT!!!....
But very weird.
 
I decided to create another Bus and set this as a New Master Bus.
Wallah!... got my missing gain restored.
So I deleted the original Bus, and renamed my new Bus to "MASTER"
AWESOME.
 
Now another point I would like to make, is that this song was originally created many years ago in Sonar 6, and it is only recently that I decided to re-visit it and use my improved mixing skills to get a more polished mix.
I located the old Sonar 6 Producer Bundle file from 2005, and imported it, (without any issues... apart from a few missing plugins that I don't have at this time), and away it all went.
 
Hmmm... a tricky one eh?!?!?
 
Cheers, and thanks for your inout.
Adrian.

AdrianNewington
So I deleted the original Bus, and renamed my new Bus to "MASTER"

Has the Vocal Reverb bus been redirected to the new Master? I was going to suggest that the reverb bus signal might might be cancelling some of the direct signal from the track.

Doesn't appear anyone ever suggested to check Gain/Volume settings in Offset mode, which would be another likely cuprit. You might re-open the oriignal bundle and check for that.

Hit "O".

Maybe not but one can click the click the Offset mode button in the Control Bar’s Mix module.

From what I can see, my Sonar X1 producer doesn't have such a feature.
Here is my Mix Module on the Control Bar.
 

 

Sorry, I should have read your signature
 
Yea, 'O' is the toggle
 
If it's enabled you will see little '+' signs next to track faders amongst others