$Expand does not work when i get one item

I prepare Odata API for mobile application, and i have a problem with $Expand. When i use this query everything works ok.

Query: .../odata/forms?$expand=FormFields($expand=FormFieldRadios)&$filter=FormId eq 1

But when i use this query:

.../odata/forms(1)?$expand=FormFields($expand=FormFieldRadios)

Expand does not work and items collection si empy.

My json results Items coolection One item

My nugets

ConfigureServices:

services.AddOData();
services.AddODataQueryFilter();
services.AddMvc(options =>
    {
        // https://blogs.msdn.microsoft.com/webdev/2018/08/27/asp-net-core-2-2-0-preview1-endpoint-routing/
        options.EnableEndpointRouting = false;
    }).SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

Configure

app.UseMvc(routeBuilder =>
{
    routeBuilder.Select().Expand().Filter().Count().OrderBy().MaxTop(250).Expand(QueryOptionSetting.Allowed);
    routeBuilder.MapODataServiceRoute("odata", "odata", GetEdmModel(app.ApplicationServices));
});

ModelBuilder

 builder.EntitySet<Form>("Forms").EntityType.Filter().Count().Expand(OdataDefaults.MaxExpansionDepth).OrderBy().Page().Select();

Form Entity

 public class Form
 {
     [Key, Required]
     public int FormId { get; set; }

     [Required]
     public int Order { get; set; }

     [Required]
     public bool Active { get; set; }

     [Required, MaxLength(255)]
     public string Name { get; set; }

     public int IsDeleted { get; set; }

     [MaxLength(255)]
     public string SuccessMessage { get; set; }

     public ICollection<FormField> FormFields { get; set; } = new List<FormField>();
 }

Odata Controller

public class FormsController : ODataController
{
    private VillageContext _db;

    public FormsController(VillageContext context)
    {
        _db = context;
    }

    [EnableQuery(AllowedFunctions = OdataDefaults.AllowedFunctions, MaxExpansionDepth = OdataDefaults.MaxExpansionDepth, PageSize = OdataDefaults.PageSize)]
    public IActionResult Get()
    {
        return Ok(_db.Forms);
    }


    [EnableQuery(AllowedFunctions = OdataDefaults.AllowedFunctions, MaxExpansionDepth = OdataDefaults.MaxExpansionDepth, PageSize = OdataDefaults.PageSize)]
    public IActionResult Get([FromODataUri] int key)
    {
        return Ok(_db.Forms.Find(key));
    }
}