Portanto, temos esse conjunto de códigos que, por algum motivo, continua atingindo o tempo limite. Não é o procedimento armazenado que está sendo executado, porque funciona bem. Além disso, se removermos o parâmetro do código c #, o código será executado. O parâmetro continua quebrando (causando o tempo limite) e não podemos descobrir o porquê.

c #:

public static PTWViewList GetList(int studynumber) 
        {
            PTWViewList tempList = new PTWViewList();
            using (SqlConnection myConnection = new SqlConnection(AppConfiguration.cnARDB))
            {
                string spName = "ardb.PTWViewSelect";
                SqlCommand myCommand = new SqlCommand(spName, myConnection);
                myCommand.CommandType = CommandType.StoredProcedure;
                myCommand.Parameters.AddWithValue("@study", studynumber); 

                myConnection.Open();
                using (NullableDataReader myReader = new NullableDataReader(myCommand.ExecuteReader())) /*this is where the code times out*/
                {
                    tempList = new PTWViewList();
                    while (myReader.Read())
                    {
                        tempList.Add(FillDataRecord(myReader));
                    }
                    myReader.Close();
                }
            }

            tempList.ListCount = tempList.Count;
            return tempList;
        }

procedimento armazenado:

CREATE PROCEDURE [ardb].[PTWViewSelect] 
    @studynumber int = NULL,
    @quoteid uniqueidentifier = NULL,
    @lineitemid uniqueidentifier = NULL
AS
BEGIN
    SET NOCOUNT ON;

    SELECT
        [Study]
        ,[LineItemID]
        ,[QuoteID]
        ,[Total]
        ,[COOP]
        ,[VendorCost]
        ,[CustCost]
        ,[LineItemNumber]
        ,[StudyTypeCode]
        ,[GroupLeader]
        ,[PTWDate]
        ,[PONumber]
        ,[POStatus]
        ,[StudyDirector]
        ,[SL_DESC_L]
        ,[SL_Code]
        ,ProjectDescription
        ,CreatedBy
        ,chARProcess
        ,CODate
    FROM
        [ARDB].[dbo].[PTWView]
    WHERE
        (@studynumber is null or StudyNumber=@studynumber)
        AND (@quoteid is null or QuoteID=@quoteid)
        AND (@lineitemid is null or LineItemID = @lineitemid)
END