Potty training help?

Any suggestions for me would be greatly appreciated. I have a 2 and a half year old that we have been working on potty training with for some time now. We started around his 2nd birthday but have exposed him to the potty before and showed him what its for and whatnot to get him comfortable with it. Now he's still in pull ups but we try to do fabric underwear during the day around the house but if we go out or for bedtime he wears pull ups. If I ask him where he's supposed to go pee and poop and he will tell you the potty but he rarely actually goes without us asking him to go and try. I have tried to tell him he needs to tell someone when he needs to go so we can help him just like I did with where he's supposed to go but he refuses to come tell anyone when he needs to go instead he hids. I know it's normal for them to hid but he's smart he knows where he's supposed to go but he hids instead of telling us or trying to get to the potty himself. 90%of the time if he has pull ups on or even sometimes fabric underwear he will just hid to go to the bathroom even tho he knows where he's supposed To go. Why is he smart enough to tell me where he's supposed to do it but won't tell me when he needs to?