EF Core的Include（）函數不適用於直接GET請求

我正在使用.NET Core 3.1構建此應用，而我的json輸出不正確。這是我想要的課程列表：

[DataContract(IsReference = true)]
public class State
{
    public int Id { get; set; }

    [DataMember]
    public string Name { get; set; }

    [DataMember]
    public List<Region> Regions { get; }

    public State()
    {
        Name = string.Empty;
        Regions = new List<Region>();
    }

    public State(string name)
    {
        Name = name;
        Regions = new List<Region>();
    }
}

它具有Regions列表，該類如下：

[DataContract(IsReference = true)]
public class Region
{
    public int Id { get; set; }

    [DataMember]
    public string Name { get; set; }

    [DataMember]
    public List<County> Counties { get; }

    [DataMember]
    public List<Report> Reports { get; }

    [DataMember]
    public State State { get; set; }
    public int StateId { get; set; }

    public Region()
    {
        Name = string.Empty;
        State = new State();
        Reports = new List<Report>();
        Counties = new List<County>();
    }

    public Region(string name)
    {
        Name = name;
        State = new State();
        Reports = new List<Report>();
        Counties = new List<County>();
    }
}

這是我的方法：

[HttpGet]
public async Task<ActionResult<List<State>>> GetReportsAsync()
{
    return await context.States.Include(x => x.Regions).ToListAsync() is IList<State> states
        ? Ok(states)
        : (ActionResult<List<State>>)NoContent();
}

這是我的DbContext ：

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    if (modelBuilder is null) throw new ArgumentNullException(nameof(modelBuilder));
    modelBuilder.Entity<Report>(report =>
    {
        report.HasOne(x => x.County).WithMany(x => x.Reports).HasForeignKey(x => x.CountyId);
        report.HasOne(x => x.Region).WithMany(x => x.Reports).HasForeignKey(x => x.RegionId);
    });

    modelBuilder.Entity<State>(state => state.HasIndex(x => x.Name).IsUnique());

    modelBuilder.Entity<Region>(region =>
    {
        region.HasIndex(x => x.Name).IsUnique();
        region.HasOne(x => x.State).WithMany(x => x.Regions).HasForeignKey(x => x.StateId);
    });

    modelBuilder.Entity<County>(county =>
    {
        county.HasIndex(x => x.Name).IsUnique();
        county.HasOne(x => x.Region).WithMany(x => x.Counties).HasForeignKey(x => x.RegionId);
    });
}

但是我沒有在json輸出中填充我的Regions列表。我應該指出，在調用另一種填充數據庫的方法然後調用該方法之後，確實可以得到預期的結果，但是如果我直接調用，則Reports列表將為空。請幫我在這裡。