MongoDB driver for .NET - id property setter never called

Working with Data Drivers
1

I have a post class which may contain product class as a property.
The product class “id” property never gets set, while “stock_quantity” does.

[BsonIgnoreExtraElements]
    public class Post {
        [BsonId]
        [BsonRepresentation(BsonType.ObjectId)]
        public string _Id { get; set; }
        
        [BsonElement("ID")]
        public int Id {get;set;}

        [BsonElement("post_name")]
        public string Slug {get;set;}

        [BsonElement("product")]
        public Product.Product Product {get;set;}
    }

    [BsonIgnoreExtraElements]
    public class Product {        
        [BsonElement("id")]
        public int id {
            get;
            set;
        }

        [BsonElement("stock_quantity")]
        public int StockQuantity {
            get;
            set;
        }
    }