I have followed the advice of other SO solution: 1. Make my class Serializeable 2. Have a default constructor for Firebase 3. Update my proguard rules (Not sure about this o
Solved, even in Kotlin it seems the variables had to be explicitly Public.
import java.io.Serializable
/**
 * Created by fyi2 on 2/21/18.
 */
class User :Serializable {
    public var displayName:String=""
    public var email:String=""
    public  var photoUrl:String=""
    public var userId:String=""
    constructor() {}
    constructor(displayName: String, email: String, photoUrl: String, userId: String) {
        this.displayName = displayName
        this.email = email
        this.photoUrl = photoUrl
        this.userId = userId
    }
}
Once that was modified, the rest worked as is.