After updating the simulated location of Location Based AR, the model keeps dropping

[yuhanhuang0420]

So far, I set simulated longitude/latitude/altitude as the coordinate which comes from UWB indoor positioning results (have been converted to latitude, longitude and altitude). I update the simulate position per second, dynamically.
In the other hand, the fixed position of glTF models was set in the same coordinate system (horizontal: WGS84 latitude/longitude set by gps-entity-place; vertical: altitude set by y position as meter height).

When one of the simulated user height or the model height is zero or both are the same value, no matter how the simulated user position is updated, everything looks reasonable.
But when the simulated user height does not match the model height, once the horizontal position starts to be updated, the model seems to move downwards after updating simulate position (even if the height is not actually changed, and the horizontal place has not changed too much).

I don’t have a clue as to what might be causing this. If anyone has any possible ideas, please let me know.
I will appreciate your help.
Thanks a lot!