[5.6 bug] FbxImportUI settings physics_asset configuration appears to have no effect

My fbx import script that used to work in 5.4 stopped creating physics asset when ran in 5.6
i checked the api and doesnt seem like it has changed between the two versions.
below is the fbx import script:
import unreal
File and destination
fbx_file_path = source_file
destination_path = import_folder
fbx_import_options = unreal.FbxImportUI()
fbx_import_options.automated_import_should_detect_type = False
fbx_import_options.import_as_skeletal = True
fbx_import_options.mesh_type_to_import = unreal.FBXImportType.FBXIT_SKELETAL_MESH
fbx_import_options.skeleton = None
fbx_import_options.physics_asset = None
fbx_import_options.create_physics_asset = True
fbx_import_options.set_editor_property('import_mesh', True)
fbx_import_options.set_editor_property('import_textures', False)
fbx_import_options.set_editor_property('import_materials', True)
fbx_import_options.set_editor_property('import_animations', False)
fbx_import_options.set_editor_property('reset_to_fbx_on_material_conflict', False)
fbx_import_options.set_editor_property('physics_asset', None)
fbx_import_options.set_editor_property('create_physics_asset', True)
Import setting
task = unreal.AssetImportTask()
task.destination_path = destination_path
task.filename = fbx_file_path
task.automated = True
task.replace_existing = True
task.replace_existing_settings = True
task.options = fbx_import_options
task.save = True
asset_tools = unreal.AssetToolsHelpers.get_asset_tools()
asset_tools.import_asset_tasks([task])

Steps to Reproduce
I have no way to auto generate the PhysicsAsset asset when importing fbx via python script. This used to work in 5.4 but the exact same python code doesnt work in version 5.6
these two line have no effect in UE5.6:
unreal.FbxImportUI.create_physics_asset = True
unreal.FbxImportUI.physics_asset = None