Where did my group color bars go?

[right beside]

First time I've encountered this and can't figure it out.

All of a sudden, about half of my groups are missing a color bar to the left of the group name in the group menu. This is also reflected in the edit window, where even though a group is selected and enabled, it bears no unifying group color.

Is this a bug or a feature that can be turned on and off? Can I just select one of these groups and tell PT to bring its color back?

How did it disappear in the first place?

In the picture, the group "New Viola" (also called 3e) is enabled, but has no color bar. In the edit window, the first two tracks make up the group. They are black and white, without a predefined color, but the group is on.




PT 10.3.5
OSX 10.8.5