Seems all the column values in GROUP BY Clause exceeds DB_BLOCK_SIZE value.

How about Normalizing HR_BASELINE tables, ur using the follwoing columns which are against the rules of normalization..

HTML Code:
Workforce_Reporting"."FINANCIALCCHIER10" "Financial_Hierarchy_10",
"Workforce_Reporting"."FINANCIALCCHIER9" "Financial_Hierarchy_9",
"Workforce_Reporting"."FINANCIALCCHIER8" "Financial_Hierarchy_8",
"Workforce_Reporting"."FINANCIALCCHIER7" "Financial_Hierarchy_7",
"Workforce_Reporting"."FINANCIALCCHIER6" "Financial_Hierarchy_6",
"Workforce_Reporting"."FINANCIALCCHIER5" "Financial_Hierarchy_5",
"Workforce_Reporting"."FINANCIALCCHIER4" "Financial_Hierarchy_4",


"Workforce_Reporting"."EC" "EC",
"Workforce_Reporting"."EC_PLUS1" "EC_Plus1",
"Workforce_Reporting"."EC_PLUS2" "EC_Plus2",
"Workforce_Reporting"."EC_PLUS3" "EC_Plus3",
"Workforce_Reporting"."EC_PLUS4" "EC_Plus4",
"Workforce_Reporting"."EC_PLUS5" "EC_Plus5",
"Workforce_Reporting"."EC_PLUS6" "EC_Plus6",
"Workforce_Reporting"."EC_PLUS7" "EC_Plus7",

Or use multiple block size's and assign the temporary tablspace to hruser with higest block size available with your operating system.

Hope you can have Multiple block size for temporary tablespaces, if its possible then you can solve the problem by assigning hruser a temporary tablespace with highest possible block size.