New Tobii user here. Just received mine in the mail and ran straight into the Tobii not working with MSFS issue (albeit working perfectly fine in general), apparently because additionally to Tobii there was still TrackIR recognized in the control settings (as mentioned by other users, MSFS has issues with both being present). For me that TrackIR entry was a “corpse” off an earlier attempt to use “OpenTrack” (didn’t work properly so I uninstalled it right away again months back).
Tip to anyone having the same issue - there is no need for elaborate resets or reinstalls of MSFS or Windows! Neither do you have to fumble around in your registry.
All I had to do was to install the newest version of OpenTrack (GitHub - opentrack/opentrack: Head tracking software for MS Windows, Linux, and Apple OSX), then right away uninstalling it again (might help if you use Revo or CCleaner instead of the standard Windows app center uninstall). That seemed to clear out those leftovers from my earlier use of the software. After a reboot and restart of MSFS, the TrackIR option in the MSFS controls menu was gone and Tobii worked straight away.
Maybe this might help somebody with similar issues.