When you go into Control Settings in MSFS: press the Sensitivities button and check if your axis appears and if you see movement on the screen when you move the lever.
If that works, MSFS “sees” the axis. In this case there is no reason why you should not be able to assign a function to it.
Another thing to check: some Axis have two flavors in MSFS. One is just Axis, the other is Axis 0-100%. Try both and see what happens…