In a shallow bowl, whisk egg, milk and Dijon mustard. In another shallow bowl, mix bread crumbs, potato flakes, ground mustard and sage. Place flour in another shallow bowl. Sprinkle pork with salt., Preheat air fryer to 400°. Dip pork in flour to coat both sides; shake off excess. Dip in egg mixture, then in bread crumb mixture, patting to help coating adhere., In batches, place chops in greased air fryer; spritz with cooking spray. Cook until a thermometer reads at least 145°, 5-6 minutes, turning once.