HITL Camera Problem

I am currently working on the PX HITL with the following configurations:

  • PX (without real camera) will be connected to PC via usb port ttyACM0
  • In sitl_gazebo, the drone iris is set up with a gymbal camera (using plugin gazebo gst plugins + geotagged image capture) which allows QGC to receive video from camera via le port UDP 5600.
  • MAVSDK will send the mission file to PX4 via the telemetry which is connected through port ttyUSB0.

With the above setting, I can control the drone with video displayed in QGC. In my mission file there are some commands to capture the photos/videos (mavlink ID: 2000 and 2500) for online obstacle detection purpose but at the end of mission, there is nothing saved in the folder of QGC.
I did the same process where the mission file is uploaded offline using usb connection between QGC and PX, and then run the simulation again (without MAVSDK), but there are still no photos or videos in QGC data folder path. In the QGC logfile, there is a message concerning camera:

foundGimbal:foundCameraAction:foundCameraMode false false false

Going deep into HITL architecture of PX4, I found out that only commands concerning motor will be sent from PX to simulator Gazebo via ttyACM0. Therefore, I assumed the issues coming from the fact that PX4 triggered the physical real camera (which does not exist in reality) but it did not trigger the simulated camera since no camera commands is sent to gazebo. My assumption is right ? In that case, there is any solution to indicate Gazebo triggering the simulated camera ? A firmware modification is needed ?