You can plateau on absolutely any diet, and on low carb plans, many times you lose fat and don't always see the scale move. I had a friend who went down 4 sizes and the scale didn't move for months. Many times you have to push through it. Many people change things up. If you go to a higher carb plan, you will need to very slowly add carbs back in or you will gain weight till your body is used to them again. Sometimes just kicking up our exercise plan can work. You can try carb cycling where you have higher and lower carb days. Did you track your food intake while on Atkins? Many people have to in order to keep losing weight? Did you drink your water? Good luck!