Bool can't add to realm

When `Bool` default value is 'true', can't save to realm
I changed the demo
```
struct ToDoItem: Realmable {
    var id = UUID().uuidString
    var text = ""
    var isCompleted = true //modified this default value
    
    static func primaryKey() -> String? {
        return "id"
    }
}
```
when I set the 'isCompleted' default value is true.
can't save the false to the realm