Hi CS.
This happens in any case, no matter if the tracks are grouped or not.
I just discovered the track name will actually update once you move to another scene with the jog wheel, after moving to another track. But just changing tracks using the track buttons or hold + jog wheel or clicking on the track in Live won't update the display on the Tranzport like it used to do.
Another Live user also talked about this on the Ableton forum.
I tried copying the tranzport script in the control surfaces folder from an earlier version of live but the problem was still there, so I'm guessing ableton changed something in the latest version which introduced this problem.