Fixed Wing HIL not working in Gazebo

I have been trying to implement hardware in the loop for fixed-wing using Gazebo. I am using the latest Pxihawk firmware and QGround control. I have noticed that the HIL framework that QGround has for fixed-wing is HilStar for xplane. I tried using that firmware but for some reasons, my plane doesn’t behave the way it should (It starts rotating and keeps on moving here and there and if I try to instruct it to do something, it doesn’t.)

So, I want to know if I should make a separate airframe for the Gazebo Fixed-wing or is there anything that I am missing?

Note that HIL with quadcopter is working perfectly its only the fixed-wing and VTOL.

I’ve tried this a while ago and it took me a while to figure out the mapping of the motors and servos. My work in progress is here: