A couple of things here…when you open the DJI app there’s no need to calibrate the drone unless you see an error message that the aircraft has fallen out of calibration. Only open the app to respond to any DJI geofencing authorizations, check camera settings, start then stop the aircraft. The drone is now primed and ready to fly, something that the MPP app can’t do.
Next step is to hard close the DJI app, don’t leave it running in the background (…this is important) Open the MPP app and wait for it to recognize your aircraft. When it does, you should be ready to execute the mission.