When creating user or searching, two_factor_auth_enabled returning null. Dotnet sdk by justeat does not handle.

I am using zendesk dotnet sdk by justeat but when i try to search for the user or create user it gives me this error Error converting value {null} to type 'System.Boolean'. Path ‘results[0].two_factor_auth_enabled What I don’t understand is that it was working earlier but now it is causing this issue. I have gone through the sdk code they have not handled this case and expect only boolean value. 
Has anyone else faced the same issue, If so is there any fix or ill need to implement the service.