selecting lanes in group editing mode problem

I’m working on combing multitracks in group editing mode (all track in a folder and group editing activated).
2 flutes and a bass track - 3 takes stacked on 3 lanes. Works great BUT…
At one spot I want to split and copy a part of the bass track only. So I deactivate group editing assuming than I now can work with that track only. But if I select that lane the same lane is selected on the other tracks. This only happens if it’s the “active” lane I select. If I select one of the other lanes it doesn’t happen.
I even tried moving the bass track out of the combing folder - same result. The tracks shown on the “master track” seems to be grouped together no matter what I do.
Design or operator error ?

No one else seen this ??