CMC CH & 7.5 Mute button issue

I’ve noticed in mixconsole (7.5) that mute doesn’t control all channels when they are linked, only the first. All other controls work simultaneously as expected.
Clicking any mute button onscreen of those of linked channels will make all linked channels mute / unmute as expected, but the mute button on cmc doesn’t do this. Not sure why. Any ideas ?