Identity/EF collection returns null

//Model/AppUser.cs
public class AppUser : IdentityUser
{
    public ICollection<Profile> Profiles { get; }
}

//Model/Profile.cs
public class Profile
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public string AppUserId { get; set; }
    public AppUser AppUser { get; set; }
}

//some razor page's cshtml
public async Task<IActionResult> OnGetAsync()
{
    StatusMessage = "";
    var user = await _userManager.GetUserAsync(User);
    if (user == null) {return NotFound($"User ID Not Found");}

    Username = user.UserName; //works as expected
    Profiles = user.Profiles; //null value
    return Page();
}