I installed the Mouse and Keyboard Center. It couldn't even find my mouse!!! (No sure what its supposed to do, because WIN 10 without it allowed me to control mouse properties) So I uninstalled it. The basic Win10 PC Settings functionality did not offer me the opportunity to change the wheel "task". (Perhaps that capability is hidden somewhere else.)
However, during that exploration, I discovered that my (recently-purchased) mouse has a wheel-tilt function. And, as it turns out, I was depressing the wheel (which ADE recognized and went into pan mode) and then tilting the wheel as a continuation of the "depress" motion (which ADE did not recognize as a pan command) - explaining the occasional "jerk" in the display when I first depressed the wheel.
Confusing this matter is that if the wheel has been tilted, when the button is released the pan cursor (i.e. the cross) does not revert to a pointer. So, Jon, it seems ADE "forgets" it's in pan mode when the wheel is tilted.
Don