hello,
I suspect you've accidentally done something that I've been trying to figure out how to do... namely disable automation on a specific track. When you are in 'small' view, the little arrow under the track name that brings up the 'view volume, view waveform' etc button goes gray when automation is dissabled. To do this you have to option click (or shift option click - one or the other!). To undo it, ie switch automation back on, repeat the procedure....
There's a thread further down the list, started by me, called 'taking automation out of 'do to all''
here where some very helpful people have explained it better than me!
I hope that helps,
Matthew