RedShift Error when using COUNT (Distinct XXX) ERROR: XX000: This type of correlated subquery pattern is not supported due to internal error

I have a small query running in RedShift through Aginity that is getting the following error:

ERROR: XX000: This type of correlated subquery pattern is not supported due to internal error

Current Query:

SELECT 'MYSCHEMA.MYTABLE.FIELDA' as obj_name,
COUNT(*) as rows, 
COUNT(DISTINCT FIELDA) as distinct_vals, 
SUM(CASE WHEN FIELDA in ('00DK','00DC','00DE','00DD','00DB') THEN 1 ELSE 0 END) as enter, 
SUM(CASE WHEN TRIM(FIELDA) IN ('',null) THEN 1 ELSE 0 END) as nulls 
FROM MYSCHEMA.MYTABLE

However if i remove the DISTINCT it runs:

SELECT 'MYSCHEMA.MYTABLE.FIELDA' as obj_name,
COUNT(*) as rows, 
COUNT(FIELDA) as distinct_vals, 
SUM(CASE WHEN FIELDA in ('00DK','00DC','00DE','00DD','00DB') THEN 1 ELSE 0 END) as enter, 
SUM(CASE WHEN TRIM(FIELDA) IN ('',null) THEN 1 ELSE 0 END) as nulls 
FROM MYSCHEMA.MYTABLE

Answer

Does it work if you use window functions in a subquery?

SELECT 'MYSCHEMA.MYTABLE.FIELDA' as obj_name,
       COUNT(*) as rows, 
       SUM( (seqnum = 1)::INT ) as distinct_vals, 
       SUM(CASE WHEN FIELDA in ('00DK','00DC','00DE','00DD','00DB') THEN 1 ELSE 0 END) as enter, 
       SUM(CASE WHEN TRIM(FIELDA) IN ('',null) THEN 1 ELSE 0 END) as nulls 
FROM (SELECT t.*,
             ROW_NUMBER() OVER (PARTITION BY FIELDA ORDER BY FIELDA) as seqnum
      FROM MYSCHEMA.MYTABLE t
     ) t