Setting Controls w/Ipac4 in Fusion. Stuck Input

I run Fusion for all of my Sega Systems as part of a large Hyperspin set up on a 4 player cabinet. I completed my 4 way controller set up in Fusion using the 3 button-iPac4 settings and everything seemed to be working well. However, when I started up Jordan vs Bird and NBA Lakers vs Celtics in Sega Genesis, the intro skips and the game acts as if I am holding down a button. Its completely stuck! When I switch back to 2 controller mode in the Fusion settings, the issue goes away. But I want to use the 4 player mode. Anyone else see anything like this?