Expression transform not working

I'm stumped. I have a mainstage concert in which some patches use the transform expression feature. However, since upgrading to a new macbook pro the feature doesn't seem to be working. Thought it might be a glitch in the concert so I made a new concert, still doesn't work!

Here's what I do: Start a new project, pick keyboard template. Play Steinway piano plugin, operate expression pedal. Piano plays, expression increases and decreases as it should, showing up in the dial at the top of the strip. So far so good.

Now, click on the Steinway piano strip, and select the midi input tab in the instrument channel strip inspector. Change controllers output from expression, 11, to volume, 7. Since the input defaults to expression, it should now be transforming expression into volume, and when I operate the expression pedal, I expect to see the volume fader of the strip move up and down. But nothing happens.

Anyone know what I might be missing? thank you!