the reason is
Negative_elevation.sh3d
Some objects need to be embedded below the floor.For example, the railings and ceiling lights below.
If the elevation cannot be negative, it floats on the floor.
Only at the highest position on the lower floor
The lights on the chandelier layer are the same
The problem is that on the lower floors, the railings and ceiling lights on the upper floors are displayed.
Not only difficult to see, but also affect your operation on the lower floors