System.InvalidOperationException: The specified cast from a materialized 'System.Int32' type to a nullable 'Country' type is not valid

I have a particular unit test that runs fine on my personal PC, but whenever I get TFS to run the test, it fails with the following exception -

System.InvalidOperationException: The specified cast from a materialized 'System.Int32' type to a nullable 'Country' type is not valid.

By following the stack trace, it has a problem with the following method -

public IEnumerable<IAddress> AddressSelectAll(long userID)
{
    using (var context = new Entities())
    {
        var addresses = context.Customers
                               .Where(x => x.UserId == userID)
                               .Select(y => new Address
                                                {
                                                    Address1 = y.Address1,
                                                    Address2 = y.Address2,
                                                    Address3 = y.Address3,
                                                    AddressID = y.AddressId,
                                                    City = y.City,
                                                    Country = y.Country != null ? (Country)y.Country : (Country?)null,
                                                    Postcode = y.Postcode,
                                                    State = y.State,
                                                    RecordEntryDate = y.RecordEntryDate,
                                                    Type = (AddressType)EFFunctions.ConvertToInt32(y.AddressType),
                                                    UserID = y.UserId
                                                }).ToList();

        return addresses.ToList();
    }
}

In case it's relevant (doubt it is), my EFFunctions class is defined as -

public static class EFFunctions
{
    [EdmFunction("Model", "ConvertToInt32")]
    public static int ConvertToInt32(string text)
    {
        var result = string.IsNullOrEmpty(text) ? 0 : Convert.ToInt32(text);

        return result;
    }
}

And my .edmx has the following in it -

<Function Name="ConvertToInt32" ReturnType="Edm.Int32">
  <Parameter Name="v" Type="Edm.String" />
  <DefiningExpression>
    CAST(v AS Edm.Int32)
  </DefiningExpression>
</Function>

Is anyone able to tell me what I'm doing wrong?