@Wizard3d Ah, it’s crashing creating the CDO for your MyEditorUtility class the second time around.
I’m not at my desk to test, so this may make no difference, but does this change help at all?
# before
editor_util = MyEditorUtility()
levels = editor_util.get_selected_assets()
# after
levels = MyEditorUtility.get_default_object().get_selected_assets()