@Exxassens Thanks again for such a quick reply and apologies for not responding before now. Had to go heads-down for a few days to finish another project. 
Anyway, my use case is, admittedly, a bit janky. And my implementation is probably somewhat cringe-worthy if reviewed by more experienced coders. Essentially this is not a game, per se. It is actually a touchscreen experience that will be featured at trade shows and will usually be run exclusively as touch. However, there will be times when one of the more savvy sales guys will grab the gamepad and drive it with that. SO, my “pawn” and the UI are enabled with both touch and gamepad controls.
The only reason I used two different IAs & mapping contexts was because for some reason, the virtual joystick and the real joystick were sending opposite inputs: pushing the stick forward sent my pawn backward on the virtual joystick, but pushing it forward on the real joystick worked as expected, so I had to add a negate modifier to one IA. In my workaround I just multiplied the input value by -1 to accomplish the same thing.
Now, all that said, after you mentioned priority, I went and looked at that a little closer. Seems I had them both at the same priority. 
So this was definitely pilot error. Modifying the priority solves the “problem.” Feeling kinda dopey…rookie mistake.
Anyway, thanks again for being so attentive. Your plugin works like a champ!!