Logic Pro X midi volume has no effect

I am at my wit's end. I have a large template using separate midi channels for each instrument articulation. Most tracks work fine but there are several on which the midi volume (CC7 in the automation) has absolutely no effect on the track's volume. I move the data point, I move that track's slider, I've even gone into the event editor and changed the value, but nothing changes. I've searched extensively on this subject to no avail. Does anyone have any idea why this might be?