SQLite and Entity Framework Core: why include doesn't work?

I use EntityFrameworkCore.SQLite v1.1.3, VS 2015, make simple WPF application, .Net 4.6
People and Orders tables are related as "many-to-many" through OrdersToPeople table in my database. I've made dbContext classes using SQLite Tools.
I use this code to check loaded data:

var list = myDbContext.People
    .Include(t => t.OrdersToPeople);
foreach (var element in list)
{
    var c = element.OrdersToPeople.Count;
    //c is always 0. Why?
}

When i load OrdersToPeople or Orders tables the same way

var list = myDbContext.OrdersToPeople

or

var list = myDbContext.Orders

, i see the data. When i make SQL-query, it returns me correct data.

Why Include does not load OrdersToPeople?

P.s. The OrdersToPeople field is virtual.

public partial class People
{
    //...fields...
    public virtual ICollection<OrdersToPeople> OrdersToPeople { get; set; }
    public People()
    {
        OrdersToPeople = new HashSet<OrdersToPeople>();
    }
}
public partial class OrdersToPeople
{
    public long Id{ get; set; }
    public long PeopleId { get; set; }
    public long OrderId { get; set; }
    public virtual People People { get; set; }
    public virtual Orders Orders { get; set; }
}