Once a program, such as a flight sim, has been started with a controller connected it will only recognize that controller until it is disconnected or ‘reconfigured’ as with a new driver etc.
you can try with the PC turned off - disconnect your thrust master x - start your PC - then start MSFS. Then go to the MSFS ‘Controls’ page and scroll through the joystick profiles to see what’s listed. If you see your thrustmaster x - then press the ‘reset to default’ or similar and see what that does. Either way - whether you see your controller listed or not - you want to reset to default settings. Then close MSFS and turn off your PC. Then restart the PC and connect the controller and make sure the PC ‘sees’ it is connected and configured. Then start MSFS and go back to the ‘Controls’ page and see if it is recognized there again.