Thanks for answering! I have managed to solved this problem by using proper MOCAP data instead of GPS.
I did not test in the QGC. But for mavros I succesfully armed the drone, which is what I really want for doing more control.
I wonder if there is any tutorial or documentation for doing low-level control, such as to do control specifically on motors, PWM, instead of using PX4 to do high-level control.
Thanks for your help again!