I am trying to edit an older project (from a few months ago). When I open it I have several groups of tracks. Some of them are nested. When I try to arm single track, I see the RED indicator going ON momentarily (on all of the tracks, instead of one), then it goes OFF and the track is not armed. This happens to all tracks inside a group. The other groups do not blink. When I however add a new midi track, I can ARM it without problems. I also have no problem arming audio tracks. I tried to ungroup and group them with no success. All routing (In/Out was checked) and looks OK.
I've spent several hours trying all kinds of things, but no luck.
If anybody has had similar issues resolved, please help.