Latitude 5480 / 7480 Stick scroll doesn't work

Folks,

I have a 5480 and a 7480 that I cannot get to stick scroll on Windows 10

I have plenty of Latitudes. The middle button stick scroll works on E7470 and older. But on the 7480 and 5480 it doesn't. Once in a blue moon, the stick scroll will work for about 2 seconds and then nothing. 

If I re-assign the middle button to another function it works fine. This is frustrating the heck out of me since I use middle button stick scroll all the time. 

I compared a couple of things on an 7480 to an E7470 (which works fine). So what jumps right out at me is that in device manager, the E7470 shows Dell Touchpad under Mice and other pointing devices, whereas the 7480 shows HID-Compliant mouse. I have the touchpad drivers installed on the 7480 and the registry on the 7480 is chock full of Touchpad references. I copied the DellTouchpad drivers from the E7470 and tried to force the 7480 to use them but Windows states that I already have the best driver installed.