Problem with customizing default identity in a MVC app.

Dear Csharpers,

I am customizing the default identity in a MVC asp.net core 6.0 project. I wanted to change the types of the Ids, thats why I inherited and have overriden the default IdentityUser, IdentityRoles na IdentityUserRoles as follows:

public class User : IdentityUser<Guid>
    {
        public override Guid Id { get; set; }
        public string FirstName { get; set; }
        public string Surname { get; set; }
        ......

        ......

        //public ICollection<UserRole> UserRoles { get; set; }
#nullable enable
        public ICollection<Listing>? Listings { get; set; }

    }

 public class Role : IdentityRole<Guid>
    {
        public override Guid Id { get; set; }
        public string Discriminator { get; set; }
        
    }

public class UserRole : IdentityUserRole<Guid>
    {
        public Guid Id {get; set;}
        public override Guid UserId { get; set; }
        public override Guid RoleId { get; set; }
    }

Then I start the application and check, if the Database is empty  => I seed an admin - create an user with new Guid for Id, then create and save Role with new Guid for RoleId, but after I try to create and add UserRole with the folowing code:

var userRole = new UserRole
                    {
                        Id = Guid.NewGuid(),
                        UserId = admin.Id,
                        RoleId = role.Id
                    };

....there comes this error:

"System.InvalidOperationException: 'The value of 'IdentityUserRole<Guid>.UserId' is unknown when attempting to save changes. This is because the property is also part of a foreign key for which the principal entity in the relationship is not known.'"

Can anyone help me to solve this issue?