I cannot give you a reasoned explanation, only suggestions.......... A few months ago I replaced my old (sound card plugged) sidewinder with a new (USB) sidewinder.
It loaded normally and has behaved itself .......
What I don't remember is making sure it was shown in the game controller window. It is, (I just checked), along with the old stick which it says properly is not connected.
Might be worth removing it from game controller and re-installing it if it isn't back there next time..... Also, even simpler, try booting up before you actually plug the stick into a USB port.
The old sidewinder developed all sorts of chip related faults, gradually losing influence until it would answer only a few controls. In fact in its last existence it was set up as a 2 axis 4 button device.