Now I know what 'Yes/No' means on the far right side of an open flex schedule screen.'
And now I know you have to remove zones from an existing flex sched before they'll be available to a new flex zone.
And now I know that you can't create a new flex sched when zero zones are available.
And a zone only being allowed in on flex schedule makes sense.
Sorry to trouble you on this one - couldn't figure it out intuitively, I guess.