ServiceStack 4 C# client async call hangs

I am using ServiceStack 4 client to access a RESTful api endpoint. I have written two methods to return a list of objects. The synchronize method returns data as expected. The async methods hangs on the line :

var response = await client.GetAsync<List<Debtor>>("api/Debtor");

This is how my methods are defined:

    public async Task<List<Debtor>> GetDebtorsAsync()
    {
        var debtors = new List<Debtor>();

        try
        {
            var client = new JsonServiceClient(GlobalSingleton.ServerURI);
            var response = await client.GetAsync<List<Debtor>>("api/Debtor");
            debtors = response;
        }
        catch (Exception ex)
        {
            throw;
        }
        return debtors;
    }

    List<Debtor> IDebtorDal.GetDebtors()
    {
        var debtors = new List<Debtor>();

        try
        {
            var client = new JsonServiceClient(GlobalSingleton.ServerURI);
            var response = client.Get<List<Debtor>>("api/Debtor");
            var r = response.GetResponseStatus();
            debtors = response;
        }
        catch (Exception ex)
        {
            var x = ex.Message;
            throw;
        }
        return debtors;
    }