Mapping IdentityUser derived to a concrete class with AutoMapper - entity-framework

Question

I have a simple AspNetCore Web Api with 2 entities a Product and a Person which derives from IdentityUser
public class Product
{
public int Id {get;set;}
public string Name {get; set;}
public Person Person {get; set; }
}
public class Person : IdentityUser
{
public string FirstName {get; set;}
}
And the ViewModel and the AutoMapper profile
public class ProductVM
{
public string Name {get; set;}
public string PersonWhoAdded {get;set;}
}
public class ProductProfile : Profile
{
public ProductProfile()
{
CreateMap<Product, ProductVM>()
.ForMember(p=> PersonWhoAdded , opt.MapFrom(model=>model.Person.FirstName)).ReverseMap();
}}
And here is my repo
`public class ProductRepo: IProductRepo
{
public IEnumerable<Product> GetProducts()
{
return context.ProductSet.Include(p=> p.Person).ToList();
}
}`
And my controller
[Route("api/[controller]")
public class ProductController: Controller
{
IMapper _mapper;
ctor(mapper){
_mapper=mapper;
}
[HttpGet]
public IActionResult Get()
{
IEnumerable<Product> _products = _repo.GetProducts();
// omitted Status codes for simplicity
return Ok(_mapper.Map<IEnumerable<ProductVM>>(_products);
}
}
The problem is it shows me null on personWhoAdded instead of the FirstName
I can authenticate and do PUSH from different users after I register and login but if I want a get to list the products and the firstName of the User it shows me null ...
Maybe there's a different approach but I am not an expert so any help would do
Thanks