do you have the real sysex set to the proper settings on the axe? what are your connections? cat5? midi?
The MFC should be sending a CC to put the Axe in/out of tuner mode when you use the switch. Check if "Tuner" is set to (CC#) 15 at the Axe I/O: CTRL page. I'm not sure it has to be CC#15, but that's the default so try that first.