Is he cowering in fear or is he just hiding? It makes a huge difference on how to handle things. If he is cowering in fear then you need professional help. It's a very young age to be showing fear and is likely to be a lifelong problem if it's not addressed properly now.
If he is just hiding then read on.
Puppies don't come with an automatic recall, and it's probably one of the top 5 questions asked on the forum so you are not alone (have a look through the puppy thread). All a puppy wants to do is explore the world and play. Btw - what is he hiding under?
For starters you need a recall word - just calling his name isn't asking him to come. You probably say his name 50 times a day and he won't know which means come to me and which means lets play - and at the moment it sounds like he may have trained himself that calling his name means hide. Then you need to teach him the word. So with him in front of you say come/here (whatever word you choose) in a light, high pitched voice and give him a treat when he comes. Slowly increase the distance.
Use a high value treat if your current rewards aren't working - hot dog, salami, cheese (treats should be cut up to about the size of your finger nail). I recommend you always have some treat handy with a puppy - your pockets should always have something in it so you can reward him every time he does what you want.
There will be times when he still doesn't come. If he ignores the recall you have several options. Firstly, try running away, make it a game - not many dogs can resist - and it makes you fun and more interesting than whatever else they are doing. You say 'baiting' him doesn't work - I assume that's with a treat, try using a squeaky toy. Again it's one of those things that puppies just love and the squeak gets there attention really well. If he's still not coming you should stop calling and go to him - you should always set him up to succeed, otherwise the calling becomes white noise and he'll learn to ignore you. If he is under a chair and you can't get him out walk away, you don't want to engage in play, try getting a recall somewhere he can't run off and hide. And I suggest you block a few escape routes for now (believe me they soon get to big to fit in small places).