I have limited experience in fixing as am still on track ir number one. Are you using track clip pro or the metal one? Have you tried both?
This may be an obvious question but have you spoken to naturalpoint? I’m thinking (in my case) the track ir kit has been reliable so maybe there is an issue with windows/ the sim? Try the other PC and maybe xplane again. Apologies if these are things already tried or suggested, am just thinking on my feet.
And let’s face it the sim has plenty of bugs we know about. In my case, on several occasions it has failed to recognise track ir and needed to be completely rebooted…