I am also facing this issue

I ran into this problem on my production server. It turned out the API response was telling me I had a bad password. I double checked and the password was fine plus my local server was running without a problem. I think the instagram API was giving the wrong error message but the correct error code 403. I suspect they flagged my IP. I'm not sure if perhaps it's a temporary thing and that I accidentally sent too many calls in a small amount of time, or if they just don't like me.

But the login code wasn't catching that the $query was empty. It just assumed things had gone swimmingly.