ASP.Net Core Web API returns Status Code 204 after successfully insert in Postman

Record is successfully inserted but 204 status code return in ASP.net Web API.

public class Customer
{
    public int CustID { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
    public string Company { get; set; }
    public bool Isactive{ get; set; }
}

Isactive bit data type in database

public interface ICustomerRepository
{
    Task<List> GetCustomers();
    Task GetCustomerByID(int id);
    Task ADDEditCustomer(Customer customer);
    Task DeleteCustomer(int id);
}

public async Task ADDEditCustomer(Customer customer)
{
    try
    {
        using (IDbConnection con = connection)
        {
            string sQuery = "USP_Customer";
            int isactive;
            con.Open();
            DynamicParameters param = new DynamicParameters();
            param.Add("@ACTION", "E");
            param.Add("@CUSTID", customer.CustID);
            param.Add("@NAME", customer.Name);
            param.Add("@AGE", customer.Age);
            param.Add("@COMPANY", customer.Company);

            param.Add("@ISACTIVE", customer.isactive);

            var result = await con.QueryAsync(sQuery, param, commandType: CommandType.StoredProcedure);
            return result.FirstOrDefault();
        }
    }
    catch (Exception ex)
    {
        throw ex;
    }
}

[HttpPost]
public async Task<ActionResult> ADDEditCustomer([FromBody]Customer customer)
{
    if (customer == null || !ModelState.IsValid)
    {
        return BadRequest("Invalid State");
    }

    return await _customerRep.ADDEditCustomer(customer);
}

It will return status code 204 in postman

I don't know how to handle in model

In my json file I will pass for post request

{
    "CustID" : 0,
    "Name" : "manish",
    "Age": 23,
    "Company": "Abc"
    "Isactive": true
}