A sub query caused the following error message under the SQL Text panel within the Tuning Lab tab.
The parser did not identify the text as a valid SQL statement.
ORA-01039: insufficient privileges on underlying objects of the view
It claims invalid SQL, insufficient rights as schema owner.
Attempting to explain plan on other people's view without the necessary privileges on the underlying objects of the view.
Use the schema that owns the tables for the Oracle connection with the SQL Optimizer for Oracle. It's required to get the necessary privileges.