Ensure your base game region matches the "CH" regional patch. To help you get this running perfectly, let me know:
Released on , version 3.0.3 is a maintenance-focused patch. While Nintendo’s official patch notes vaguely mention that "several issues have been addressed to improve the gameplay experience," technical deep-dives suggest a more specific purpose. Mario Kart 8 Deluxe -NSP--CH--Update 3.0.3-.rar