Hi Sloppysmusic,
I do not have the GTN 750. The frequency swapping works both if I click the toggle and if I use the shortcut. I just can't change the standby frequency by clicking on the knob from say 133.7 to 133.8...., also can't find a keyboard shortcut to change it.
Its odd Com1, Nav1, Com2 and Nav2 I can't change but the ADF down below I can.
Might try removing the add on and reinstalling.