Disappearing volume envelope line

Experiencing a weird issue with volume automation envelope.  On a few tracks the volume automation envelope line will frequently disappear (i.e. the green volume level line that appears when you have a track in automation mode).   I can easily get it back by switching to clip mode then back to automation mode and the volume envelope line re-appears, but it's a total hassle of constantly switching back and forth.  The automation works, I just can't see the envelope line.  It's only happening on two tracks which is also weird.
 
Appreciate any advice.