Fail to initialize the drone with GPS global origin when disabling GPS

I’m working on a simulator, and I’m trying to fly a drone when the GPS is disabled.
In the QGC:
EKF2_AID_MASK => value 24
EKF2_HGT_MODE => Vision

Now, I’m sending the mavlink msg (#48): mavlink_msg_set_gps_global_origin_pack()
with my made up lat, long and alt.
Still, when I read the telemtry->position, I get “nan” for all coordinates.
Do you have any idea how do i “teach”/“set” the drone with its global location?