$_SESSION variable not setting in AJAX call - php

Question

I wrote this call for user authentication:
$( '.sign-in' ).click( function(e) {
e.preventDefault();
var logincall = $.ajax({
type: "POST",
url: "../snippets/auth.php",
data: { username: $('#id_email').val(), password: $('#id_password').val() }
});
logincall.done(function( result ) {
alert( 'finished: ' + result );
if( result == 'valid' ) {
location.reload();
} else {
$( '.warning' ).toggleClass('hidden');
}
});
logincall.fail(function( jqXHR, textStatus ) {
alert( "Request failed: " + textStatus );
});
});
and here's the auth.php function
if( isset($_POST['username']) && isset($_POST['password']) ) {
$username = $_POST['username'];
$password = md5($_POST['password']);
$query = "SELECT COUNT(*) FROM member WHERE username='$username' AND password='$password';";
$result = $mysqli->query($query);
$result = $result->fetch_array(MYSQLI_ASSOC);
if( $result['COUNT(*)'] !== 0 ) {
$_SESSION['logged'] = true; //this sets
$query = "SELECT id, level FROM member WHERE username='$username' AND password='$password';";
$result = $mysqli->query($query);
$result = $result->fetch_array(MYSQLI_ASSOC);
$_SESSION['uid'] = $result['id']; //this DOES NOT set
$_SESSION['lvl'] = $result['level']; //this DOES NOT set
echo json_encode('valid');
} else {
echo json_encode('invalid');
}
}
The odd thing is, if I navigate directly to
myurl.com/snippets/auth.php?username=myusername&password=mypassword
it DOES set the other two session variables, but I can never get index.php to pick them up.
I even added that refresh line to it to ensure it could pick them up, and it gets $_SESSION['logged'] just fine, but not ['uid'] or ['level']