IDT vs Webi query

[first_last]

I have two columns:

• Data Source Sql: CLOB
• Data Source Table: VarChar2(4000); the results of using Oracle's LISTAGG() function

I have two filters:

• Data Source Sql Matches Pattern

REGEXP_LIKE( TABLE.CLOB_FIELD, @Prompt(Search pattern), 'i' )

• Data Source Table Matches Pattern

REGEXP_LIKE( (results of listagg), @Prompt(Search pattern), 'i')

I'm able to use both dimensions and both filters in an IDT query successfully.

Attempts to use these filters and dimensions has mixed results:

• Using the Data Source Sql field (without additional restrictions), it generates an error:

An internal error occurred while calling 'processDPCommandsEx' API. (Error: ERR_WIS_30270) (Error: INF )

• Using the Data Source Sql Matches Pattern filter does not create an error.
• Using the Data Source Table does not create an error.
• Using the Data Source Table Matches Pattern filter does not create an error.

I'm guessing that I'll need to cast the CLOB field to a VARCHAR2() to get this to work.

Why is there a difference between the two tools?