FM Pass-through SQL issues

[BIengineer]

The following query subject, utilizing two databases from each their own data source and running with Pass-Through SQL, with Oracle SQL on the DB side:

Select
   *
From
   CDB.PRODUCT as PRODUCTS
Where
   PRODUCTS.PRODUCT_ID not in (Select PRODUCT_ID from REPORTS.PROTECTED_ID);

Gives the following errors:

RQP-DEF-0177 An error occurred while performing operation 'sqlPrepareWithOptions' status='-9'
UDA-SQL-0107 A general exception has occurred during the operation "prepare"
ORA-00933 SQL command not properly ended