Problem is intermittent. Chain will float in the space between large and small chainring and crank will spin freely, as ygb described above. What I'd like to try is to get the chain out of the way, release cable tension, and see how freely the cage pivots back and forth. Maybe the cage pivot is gunky or dirty.

I also want to check how freely the cable slides through it's routing. I figure either the cable doesn't fully release when the mouse ears go down, or the cable has slack and the FD cage doesn't pivot all the way to consume cable slack for some reason. I need to think of a good way to get the chain out of the picture without removing it, as it is campy with no quick-link.

I'll post my findings probably after this weekend.