Fetching from in-memory database not working

I started to use Effort for unit testing.

Here is my code for initialization:

    private IUnitOfWork unitOfWork;

    [TestInitialize]
    public void SetupTest()
    {
        DbConnection connection = Effort.DbConnectionFactory.CreateTransient();

        var context = new STContext(connection);

        context.Fakturas.Add(new Faktura { ID = 1, FakturaNo = 1000, OwnerID = 1 });
        context.Fakturas.Add(new Faktura { ID = 2, FakturaNo = 1001, OwnerID = 1 });

        context.Products.Add(new Product { ID = 1, Name = "ProductA", Price = 50 });
        context.Products.Add(new Product { ID = 2, Name = "ProductB", Price = 100 });

        context.Orders.Add(new Order { ID = 1, FakturaID = 1, ProductID = 1, Quantity = 1 });
        context.Orders.Add(new Order { ID = 2, FakturaID = 2, ProductID = 1, Quantity = 1 });

        unitOfWork = new UnitOfWork(context);
    }

Then when I debug test I can see in debugger that those values from the code above are there, they are inserted in in-memory database, but fetching queries don't return them. Here is the image from debugger:

This is one of the queries which returns 0 elements return unitOfWork.Context.Products.ToList();

Anyone knows what might cause the problem?