TO/GA button no longer brings up flight director

[Karmah]

I own the Black Square Analogue gauge King air and use it with the TDS GTN750xi, and when the GTN 750 is selected using the hot swap function, the TO/GA button no longer brings up the flight director on the artificial horizon.  The function works when I select any other combination of the GNS530, kns-80, but fails when the 750 is selected