rogeriodec
Guys, if you read the post 1, you would know that there are no lock or mute ...

there was a first post ?

not sure why you never replied to a good question.
Craig asked.

AndertonUnfold the Take Lanes and let's see what's happening there.

or steve's

stevecWhat happens if you expand the Track Lanes - any difference?

or myself

Chuckebabypossibly something to do with take lanes ? did you have multiple takes on those tracks ?

 
and yes, takes can be "Locked".
 

chuckebaby
not sure why you never replied to a good question.
Craig asked.

AndertonUnfold the Take Lanes and let's see what's happening there.

or steve's

stevecWhat happens if you expand the Track Lanes - any difference?

or myself

Chuckebabypossibly something to do with take lanes ? did you have multiple takes on those tracks ?

 
and yes, takes can be "Locked".
 

I did not answer because all the questions were not confirmed, ie nothing different about the lanes.
Thanks.
 

im sorry if im misunderstanding here, im only trying to help.

rogeriodec  ie nothing different about the lanes.

 
does that mean this track (you are having issues with) does NOT have takes in it ?
you recorded it using "Overwrite Recording" ?
 
Myself, I remember being puzzled because when I selected Flatten Comp on the pop-up menu.
The comp is mixed down to a new Take lane named Comp. The new take is locked.
 
However if you didn't use take lanes, this wouldn't be the case.
maybe it is a bug. what ever the case, I hope it all works out for you.

I'm reviving this topic after a few months because this problem continues on other projects, even after upgrading to the latest versions of Sonar.
I have not figured out the cause of the tracks become gray, but at least I found a solution: When you add or delete a Synth, the track backs to normal color.
 
Before:

 
After insert (or delete) any synth: 

 
There is no explanation for this, except that it's ANOTHER BUG.
 
For those who want to do the simulation, here is the link of the project, mentioned in the images (I apologize, it has more than 10 instances of Kontakt, I could not remove just to keep the symptom):
https://drive.google.com/file/d/0B81wA4UHCedmVzFfMWNDTER4d0E/view?usp=sharing
 

Thanks.
I have had the exact same thing happen and found this thread.  I inserted a simple instrument track to the bottom (TTS-1) and all was fine with my greyed out tracks.  I then deleted the TTS-1 track and moved on.
There were 2 takes in the comp lanes and when you expand the comp lanes, the main track becomes colored while the comps remain grey.  I had the exact same thing on other tracks but it all remained colored.
A bug or did I do something wrong?

It may appear you are locking the Synth track somehow.
Next time this happens open Piano roll view and try unlocking the synth from the H-Track List pane.
This looks like a classic case of a locked Synth. Locking the data in the Synth will NOT allow you to edit and WILL turn the clip grey. -Thus Deleting the Synth resets the lock.
 

 
See those locks up in the top right ?

chuckebaby
See those locks up in the top right ?

When I press those locks, the piano roll notes get grey but not the clips in track view.

When this happens again, try Holding Shift and clicking the ghosted clip. This has happened to me in the past when working with AudioSnap and other random glitches. Shift + Clicking brought the greyed out clips back to life. Lemme know if this helps!

RSMCGUITAR

chuckebaby
See those locks up in the top right ?

When I press those locks, the piano roll notes get grey but not the clips in track view.

hmmm. good point.