There are only 2 ways to break up groups
1. Right-click on one of the tracks you suspect is grouped in the console (the console is the only place to group and un-group tracks) and select "DISSOLVE GROUP"
2. You can also check the tracklist to the left of the Arrange View and stretch it right to show the Grouped Tracks.
This is my problem - dissolve groups is disabled because they aren't grouped. The option to create a group is there...
Looking further, these all seem to be midi tracks. They seem to be in a secret group in the mixer.