Moving Platform beacon follows, height is abnormal

Once the QuadPlane and beacon are powered on and connected, the Dual GPS for yaw is initialized. When preparing to take off, GCS shows that the QuadPlane height (relative altitude)is not 0, and the drop is very large, sometimes negative n meters, sometimes positive n meters, but the take-off point is always at the same position. The attached picture is a screenshot of the altitude displayed on the Mission Planner during the flight.

However, when QuadPlane is turned on alone and the beacon function is not connected, the height is displayed normally.

Experimental configuration
QuadPlane Flight Control:CubeOrange
QuadPlane firmware: ArduPlane 4.4.0
Beacon flight control: CUAV V6X
Beacon firmware: ArduRover 4.2.3
Parameter setting reference link: Moving Platform Takeoff and Landing (Ships, Trucks, etc.) — Plane documentation

After experiments, the QuadPlane must be powered on again 3-4 times before the height returns to normal.

I also tried to modify the parameters on the Plane side: EK3_SRC1_POSZ = 3(GPS) or 1(baro), but it had no effect.

Has anyone encountered this situation?
Is there any solution?
If you have any ideas or suggestions, please feel free to submit them. thank you very much.