iOS Parse PFObject Subclassing with Swift Behaviour

I have a strange issue, my subclassing works in all my view controllers except one.

I have imported everything that is required, but this one class is giving me the

"Missing argument for parameter 'className' in call"

My subclass

import Foundation
import Parse

class Session : PFObject, PFSubclassing {

    class func parseClassName() -> String {
        return "Session"
    }

}

// i have removed the non important info

I perform the

Session.registerSubclass()

In the app delegate

In EVERY class I have i can create a session via

var se = Session()

But in this one class, this will not work.

The class

import UIKit
import Parse

class PurchaseViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        var se = Session()
        // gives me an the above error
    }

}

I've tried deleting the class, creating a new one even with a new name - still does not work.

MORE INFO

Ok... something made me try removing some local class Vars from the classes where the object creation works, I found that by removing

let currentUser = PFUser.currentUser()! as! FighterUser

// This is my subclassed PFUser object

Causes that class to throw there error, and adding this var into the ViewController that was not working before stops the error

Any logic to how / why this occurs? A bug ?

This works

import Parse
import UIKit

class PurchaseViewController: UIViewController {

let currentUser = PFUser.currentUser()! as! FighterUser

override func viewDidLoad() {
    super.viewDidLoad()

    var se = Session()

}

More Info 2

Even just adding