No progress

I have been on a calorie deficit trying to cut weight and fat, been eating high protein low carb low calorie meals. Hitting the treadmill 6 days a week 10 incline 3.3 speed for an hour burning 630 calories then I either do an upper body day or a leg day. Been hitting it for 3 weeks now first week noticed a definite difference. But haven’t seen any progress since any advice why it looks like nothing is happening anymore?