As you can see from the image of my setup in "Tungsten" the track below the orange track has lost all color and every clip in the track is the same.  The background has changed from a charcoal grey to a light grey and the note and control data has become a slightly darker grey making it hard to see.  It was green (I think) and I hadn't adjusted the color scheme in the "Clip" panel where all was set at 'default'.

 
I've tried re-launching Sonar with no change.  It's not a work-stopping problem but it is worrying as I wait for the other shoe to drop.

Solved.  Strange "linear" "shapes" had appeared from nowhere in my event list for that track.  I have no idea where they came from since I am entering everything into these tracks manually and I didn't put them in there.  Well, at least I will know if it ever happens again.

Track Inspector is probably set to automation instead of clips.

Hi. I saw you got it sorted, but..
From the picture, it seems like the clip is muted.
Short cut "K".
All the best.