I have set up the Push URL for my app for "Push Checkin's by this consumer's users" and my link is "https://foursquareapi.pureprofile.com/FourSquare/FourSquareRealTimeUpdate". Even, I am getting an response from your end where it's value is NULL. I am getting object value like "{"id":null,"createdAt":null," type":null,"timeZone":null,"user":null,"venue":null}".
You can see id, createdAt, type, timeZone, user, venue value NULL.