I have a software suite that reads in a URDF and uses that model in it's controller. I simulate this in Gazebo. This has worked for a while, but I'm in the process of switching from Gazebo to Mujoco. Converting the URDF to a Mujoco model was really easy, but with one issue. I have a starting orientation for my model, and when I apply it the starting orientation is 'flipped'. I can alleviate this problem by using the negative of all axis (i.e. 0 0 1 becomes 0 0 -1). However, that breaks my URDF-based controller code, since the axis aren't consistent. What's interesting is that if I don't use a free joint, my orientation is fine, however the robot floats since it's latched to the world. Why is the free joint changing the orientation of my axis? Thank you.