For right now, do on leash recalls. Don't use the word come unless you can be sure your dog is going to come... otherwise, what are you teaching? The dog so far doesn't have to come when you ask him to come.
Put him on a long leash, run away the other way to the end of the leash, ask your puppy to come (this is when you can use come, as you can make sure the dog comes), get excited, and throw a party with lots of praise, and cookies when he comes. If he doesn't come, just reel him in, and praise him for coming. Coming has to be something the dog wants to do, and at first, they often need rewarding, and the leash reeling to understand what you want.
You can progress to restrained recalls with a partner... works really well in a hallway. One of you hold the puppy on leash, the other run away calling the puppy and acting crazy to get the puppy good and excited, then the person holding the puppy lets (what is hopefully by then a really excited puppy) go and the puppy runs to you for more partying of praise and cookies. Make it a game. Keep it fun. Keep the puppy happy. Keep it short and sweet. If the puppy doesn't come, the person holding the puppy can walk him part of the way down to the other, or you can come in closer. You can even employ your daughter in the restrained recall since he already is bonded to her.
I would also step up the value of the reward. Make the salmon treat recipe on this site, or get hot dogs, or zukes (salmon variety is good and smelly), or natural balance rolled dog food which is referred to by many as puppy crack. The zukes are already tiny, and natural balance rolls, and hot dogs can be cut up tiny.
I do agree with others that it sounds like the puppy is shutting down. Keep everything positive. Don't give any negative reinforcement right now... no tapping his butt. Make it all fun right now, and ignore any failure. Your puppy is already showing stress from failure. It doesn't sound like the puppy completely understands sit is even an expected behavior yet. Go back to feeding and lots of praise for doing what you asked. Until he is more confident, you need to keep your criteria low. Don't have expectations of where your dog should be by when. Dogs progress at different rates.