If you leave the mic plugged-in, does it show-up in the Windows Control Panel? If Windows doesn’t see the mic until you un-plug it and re-plug it in, Audacity won’t see it either. (I think this a Windows/driver issue… I don’t think it has anything to do with
What might be happening is that Windows is selecting something else as the default recording source, but then it switches when you “actively” plug-in a mic. You can select your default recording device via the Windows Control Panel, but it might “permanently” revert to something else when un-plug the mic… I’m not sure…
If Windows makes the mic default recording device the second time you plug it in, it “should” do so the first time, unless you unplugged some other input before you connected the mic the second time. This made me think the problem could merely be that the connection is weak and you needed to push it in more firmly.
Nobody anywhere said either Windows or Audacity natively supports stereo mics, either. If you plug it in and it doesn’t electrically “look right” to windows, anything is possible. That’s an undefined condition.