Flatten a Track Stack
You can flatten a Track Stack, in which case the subtracks again become normal tracks.
Do one of the following:
• Select either the main track or a subtrack, then choose Track > Flatten Track Stack from the Tracks area menu bar.
• Control-click the track header of the main track or a subtrack, then choose Flatten Track Stack from the shortcut menu.
I don't think you've done anything wrong and the only way to fix things might be to quit Logic and reboot your computer at worst.
I have found v10.0.2 has some very strange display bugs. I changed screensets and the Track Header area became so wide that the Arrange area and regions were no longer visible. When I tried to resize the area, the volume sliders and panpots were duplicated several times and still filled most of the screen. I kept swapping screensets until it resolved.
You should just report this and hope that 10.0.3 arrives quickly....
Eli: sorry, I misunderstood your advice and now understand it, and have flattened the Stack - which was not part of the problem:
mt100uk: nail on the head. This track is an Automation subtrack. According to the manual p. 534, we can create as many of these as we want. I must've clicked the little triangle at some point without understanding it's true purpose. Very handy tool! thanks.