您需要添加：
按列1、列2分组
使它工作。不确定这是否是你想要的坚韧。当使用任何聚合（总和，最大值，最小值等），你将总是需要分组任何没有聚合。所以在你的情况下，两列不只是1。或者你也可以总和（col1）和总和（col2）。
因此，可以选择：

SELECT 
   sum(Col1),
   sum(Col2),
   SUM(Col3 + Col4) AS 'In_Progress'
FROM
(
   SELECT
      COUNT(case when IO_Account_Handler_Contact IS NULL THEN 1 ELSE 0 END) AS 'Col1',
      COUNT(case when Issuing_Country_Name ='U.S.A' AND Internal_status IN ('OPEN-RELEASED','OPEN-CORRECTED') THEN 1 ELSE 0 END) AS 'Col2',
      COUNT(case when Issuing_Country_Name ='U.S.A' AND Internal_status = 'For Issuance'  THEN 1 ELSE 0 END) AS 'Col3',
      COUNT(case when Issuing_Country_Name ='U.S.A' AND Internal_status = 'OPEN-ACCEPTED' AND Completed_Quality_Review IS NOT NULL  THEN 1 ELSE 0 END) AS 'Col4'
   FROM Sales_Market
) tmp

或

SELECT 
   Col1,
   Col2,
   SUM(Col3 + Col4) AS 'In_Progress'
FROM
(
   SELECT
      COUNT(case when IO_Account_Handler_Contact IS NULL THEN 1 ELSE 0 END) AS 'Col1',
      COUNT(case when Issuing_Country_Name ='U.S.A' AND Internal_status IN ('OPEN-RELEASED','OPEN-CORRECTED') THEN 1 ELSE 0 END) AS 'Col2',
      COUNT(case when Issuing_Country_Name ='U.S.A' AND Internal_status = 'For Issuance'  THEN 1 ELSE 0 END) AS 'Col3',
      COUNT(case when Issuing_Country_Name ='U.S.A' AND Internal_status = 'OPEN-ACCEPTED' AND Completed_Quality_Review IS NOT NULL  THEN 1 ELSE 0 END) AS 'Col4'
   FROM Sales_Market
) tmp
group by Col1,Col2