could not be translated and will be evaluated locally. EF CORE

Question

The SQL WHERE clause is not being generated when using properties of my base class.

The following example is a basic version of the problem:

Exception message

Microsoft.EntityFrameworkCore.Query:Warning: The LINQ expression 'where (new PackageViewModel() {CreatedByUserName = [p.CreatedBy].UserName, Id = [p].Id}.CreatedByUserName == "Ivan")' could not be translated and will be evaluated locally.

public class BaseViewModel
{
    public String CreatedByUserName { get; set; }
}

public class PackageViewModel : BaseViewModel
{
    public Guid Id { get; set; }
}

public class myTest
{
    public void Test()
    {   
       var query = _dbContext.Set<Package>().Select(p => new PackageViewModel()
        {
            CreatedByUserName = p.CreatedBy.UserName,
            Id = p.Id
        });

        var param = Expression.Parameter(typeof(PackageViewModel), "p");
        var exp = Expression.Lambda<Func<PackageViewModel, bool>>(
            Expression.Equal(
                Expression.Property(param, "CreatedByUserName"),
                Expression.Constant("Ivan", typeof(String))
            ), param
        );

        var result = query.Where(exp).ToList();
    }
}

If I try with:

var param = Expression.Parameter(typeof(BaseViewModel), "p");

It works, but then it doesn't work with other properties like Id, because they doesn't exist in the base class.

The problem is that in my final version I have some dynamic where’s over properties that are in my main class and others that are in my base class; which will result in something like this : ( p => p.Id == "…" && p.CreatedByUserName == "…")

Questions

Is this a bug?

Why do properties that are in my base class only evaluate locally?

Is there a workaround?

Is the solution to copy all properties from my base class to all my main classes?

Further technical details

EF Core version: 2.0.3

Database Provider: Npgsql.EntityFrameworkCore.PostgreSQL 2.0.1

Operating system:

IDE: Visual Studio 2017 15.7.2