If VCAs to Meter works, I believe the VCA voltage should be present on the '13 card, whether it loops through the Multiplex card or not, as the meter send is sent after this. If you set the small fader to Input mode, does that work? If it does, signal is present on the '13 card. Set the small fader to Output; does that work? If not, then the problem in is the '13 card, which you can swap out with one from a known working strip. The fact that Float doesn't work implies signal doesn't leave the '13 card to Quad Bus or Matrix.