EF Core w/ Sql Server one-to-many relationship not working

Question

I'm trying to create a simple RESTful API that can retrieve information from a Sql Server DB. I'm using .Net Core, together with EF Core for ORM.

I have mapped two tables in my database by foreign key. However, when i try to implement the relationship in EF core, it seems that no rows exist in the BaseStats table that reference the given champion row in the Champions table.

I get the following result when making the API call:

{
"championId": 1,
"championName": "Vladimir",
"baseStats": null
 }

It seems that EF core somehow doesn't recognize the relationship. I must have missed something.

Any advice would be greatly appreciated :) Below is my code. Thanks in advance.

Principal entity:

public class Champion
{
    public int ChampionId                  { get; set; }
    public string ChampionName             { get; set; }

    public ICollection<BaseStat> BaseStats { get; set; }
}

Dependent entity

public class BaseStat
{
    public int      BaseStatId { get; set; }
    public int      StatTypeId { get; set; }
    public decimal  Base       { get; set; }
    public decimal  Growth     { get; set; }

    public Champion Champion   { get; set; }
}

DB context

public class Context : DbContext
{
    public DbSet<Champion>  Champions { get; set; }
    public DbSet<BaseStat>  BaseStats { get; set; }

    public Context(DbContextOptions<Context> options) : base (options)
    {
        //
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<BaseStat>()
            .HasOne(p => p.Champion)
            .WithMany(b => b.BaseStats);
    }

}

Controller

[Route("api/[controller]/[action]")]
public class ChampionController : Controller
{

    private readonly Context _context;

    public ChampionController(Context context)
    {
        _context = context; 
    }

    public async Task<JsonResult> Stats()
    {
        var champ = await _context.Champions.FirstOrDefaultAsync(c => c.ChampionId == 1);
        return Json(champ);
    }

}

Answer 1

I updated the stats action in my controller according to Ivan Stoev's answer.

public async Task<JsonResult> Stats()
{
Champion champion = await _context.Champions
    .Include(c => c.BaseStats)
    .FirstOrDefaultAsync();
    return Json(champion);
}

While the action returns the correct information, when i make the API call through the browser, it seems to keep loading as if the call doesn't end. (spinner in browser tab, google chrome)

While at the same time, i can't make the API call in Postman without getting the following error:

Could not get any response
There was an error connecting to http://localhost:50185/api/champion/stats.
Why this might have happened:
The server couldn't send a response:
Ensure that the backend is working properly
Self-signed SSL certificates are being blocked:
Fix this by turning off 'SSL certificate verification' in Settings > General
Client certificates are required for this server:
Fix this by adding client certificates in Settings > Certificates
Request timeout:
Change request timeout in Settings > General

Does anyone have an idea as to what might cause this?