There is a lot of confusion when dealing with layers within styles especially with labels. For instance, today I got a case where customer (rightfully so) asks why the Parcel Label that is shown in C-PROP-LINE-TEXT layer in drawing settings is being turned off if C-PROP-BRNG layer is turned off. Here, we are talking about specific _AutoCAD Civil 3D (Imperial) NCS.dwt, although other templates should behave the same. To demonstrate this issue I created parcel on this template and displayed all segment labels (using Bearing over Distance style). Then when C-PROP-LINE-TEXT or C-PROP-BRNG layers are turned off the segment labels are turned off on the entire parcel. So it appears as that one object belongs to two layers…..
So you may ask yourself…why? I have to tell you, this is as designed and this is to help users get some flexibility? Remember how in Civil 3D styles and objects are separated so that one object such as surface, for example, can be displayed in many different ways.
As you know, objects (in this case segment labels) are created in specific layer that is assigned in drawing settings (right-click on drawing is Settings tab>Edit Drawing Settings) for these objects (C-PROP-LINE-TEXT). At the same time, object’s label are also displayed in the style that is assigned to that label (C-PROP-BRNG). That allows users to change styles and still be able to see objects (segment label) in the layer assigned in drawing settings. Otherwise, any time you change your style object layer would need to change, right? So, to prevent this from happening product design implemented this workflow.
To visualize it, see following screen shots in which we selected different segment label style which uses “test” layer in layer style settings. remember, your object is still in C-PROP-LINE-TEXT layer. This expectably will show label using different style. Turning off this layer will turn off only the label that is in “test” layer, while other that belong to C-PROP-BRNG will stay on.
Again, this is as designed. I hope this clarified it a little for all..