I just sat down in the control room, and discovered the PMC (and everything else) unlocked. I relocked the PMC, but the MC wasn't coming back. After a moment of looking around, I discovered that the WFS were on, and railing. I ran the "turn WFS off" script, and the MC came back right away, and the WFS came on as they should.
We need to relook at the WFS script, or the MC down script, to make sure that any time the MC is unlocked, no matter why it unlocked, the WFS output is off and the filter histories are cleared.