I've got a few display bugs I encounter regularly (the multi-dock is a usual suspect) but this new one confounded me.
 
I've Auto-Track Zoom enabled, and I added a soft-synth and now whenever I switch tracks the zoom disappears and all tracks are minimized. I can manually expand it, even set it as default, but whenever I switch focus it goes back to being minimized. Also tried toggling auto-track zoom and still nada. So now, for the remainder of mixing this project, I have to manually drag expand EVERY TIME I SWITCH TRACKS. Pblt.
 

You are running X3E I assume?
Do you full have steps to reproduce from a brand new project?
 
Cheers...

Just a shot in the dark here... If you select all tracks and drag does the auto zoom take?

Yah, X3E. Couldn't repro, this was one of those weirdo things that popped up in a single project. 
 
Annnnnd, eventually it just went away (so far). Without even a save or restart it just started working again. Oh technology.